add `since` query string support to list issue comment

* Issues can be closed via API

* Error-checking is nice xD

* EditIssueOption.Status => State

* Use const instead of string-literal

- Fill Milestone and Assignee field when available in webhook payload

- Detect non-exist commit and return 404 not 500

Try to merge into develop branch ASAP, then continue minor fixes afterwards.

commit 0afcb843d7
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 17:13:29 2016 -0600

    Removed Upload stats as the upload table is just a temporary table

commit 7ecd73ff55
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:42:41 2016 -0600

    Fix for CodeMirror mode

commit c29b9ab531
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 08:03:33 2016 -0600

    Made tabbing in editor use spaces

commit 23af384c53
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:56:46 2016 -0600

    Fix for data-url

commit cfb8a97591
Merge: 7fc8a89 991ce42
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:42:53 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit 7fc8a89cb495478225b02d613e647f99a1489634
Merge: fd3d86c c03d040
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:40:00 2016 -0600

    Merge branch 'feature-create-and-edit-repo-file' of github.com:richmahn/gogs into feature-create-and-edit-repo-file

commit fd3d86ca6bbc02cfda566a504ffd6b03db4f75ef
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Sun Jul 31 07:39:44 2016 -0600

    Code cleanup

commit c03d0401c1049eeeccc32ab1f9c3303c130be5ee
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 29 15:38:23 2016 -0600

    Code cleanup

commit 98e1206ccf9f9a4503c020e3a7830cf9f861dfae
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:36:01 2016 -0600

    Code cleanup and fixes

commit c2895dc742f25f8412879c9fa15e18f27f42f194
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 18:24:04 2016 -0600

    Fixes per Unknwon's requests

commit 6aa7e46b21ad4c96e562daa2eac26a8fb408f8ef
Merge: 889e9fa ad7ea88
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Thu Jul 28 17:13:43 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	modules/setting/setting.go

commit 889e9faf1bd8559a4979c8f46005d488c1a234d4
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:09:18 2016 -0600

    Fix in gogs.js

commit 47603edf223f147b114be65f3bd27bc1e88827a5
Merge: bb57912 cf85e9e
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:07:36 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go
    	public/js/gogs.js

commit bb5791255867a71c11a77b639db050ad09c597a4
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 22 14:02:18 2016 -0600

    Update for using CodeMirror mode addon

commit d10d128c51039be19e2af9c66c63db66a9f2ec6d
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 16:12:57 2016 -0600

    Update for Edit

commit 34a34982025144e3225e389f7849eb6273c1d576
Merge: fa1b752 1c7dcdd
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Tue Jul 19 11:52:02 2016 -0600

    Merge remote-tracking branch 'gogits/develop' into feature-create-and-edit-repo-file

    Conflicts:
    	modules/bindata/bindata.go

commit fa1b752be29cd455c5184ddac2ffe80b3489763e
Author: Richard Mahn <richard_mahn@wycliffeassociates.org>
Date:   Fri Jul 15 18:35:42 2016 -0600

    Feature for editing, creating, uploading and deleting files

Closes #3182

* Add AddCollaborator API Endpoint

* Add optional Permission to AddCollaborator endpoint

* Use APIContext

* Implement wiki mirroring, add Update mirrors operation to admin dashboard

* bindata.go update after merge

* Implement checking Git repo endpoint existence, support for BB included

* Remove admin dashboard operation
Fix bindata.go

* Apply gofmt to repo model file

* Try to remove bindata from PR

* Revert accepted wiki names change in favor of better system

* Remove unused imports

* render code view server side

* remove debug print

* fix multiline selection bug

* change string concatenation to bytes.Buffer for efficiency

* Fix newlines added by previous for hljs

* fix selection highlighting

* make css changes in .less

* Add support for federated avatars

Fixes #3105

Removes avatar fetching duplication code
Adds an "Enable Federated Avatar" checkbox in user settings
(defaults to unchecked)

Moves avatar settings all in the same form, making
local and remote avatars mutually exclusive

Renames UploadAvatarForm to AvatarForm
as it's not anymore only for uploading

* Run gofmt on all modified files

* Move Avatar form in its own page

* Add go-libravatar dependency to vendor/ dir

Hopefully helps with accepting the contribution.
See also #3214

* Revert "Add go-libravatar dependency to vendor/ dir"

This reverts commit a8cb93ae64.

* Make federated avatar setting a global configuration

Removes the per-user setting

* Move avatar handling back to base tool, disable federated avatar in offline mode

* Format, handle error

* Properly set fallback host

* Use unsupported github.com mirror for importing go-libravatar

* Remove comment showing life exists outside of github.com

... pity, but contribution would not be accepted otherwise

* Use Combo for Get and Post methods over /avatar

* FEDERATED_AVATAR -> ENABLE_FEDERATED_AVATAR

* Fix persistance of federated avatar lookup checkbox at install time

* Federated Avatars -> Enable Federated Avatars

* Use len(string) == 0 instead of string == ""

* Move import line where it belong

See
https://github.com/Unknwon/go-code-convention/blob/master/en-US/import_packages.md

Pity the import url is still the unofficial one, but oh well...

* Save a line (and waste much more expensive time)

* Remove redundant parens

* Remove an empty line

* Remove empty lines

* Reorder lines to make diff smaller

* Remove another newline

Unknwon review got me start a fight against newlines

* Move DISABLE_GRAVATAR and ENABLE_FEDERATED_AVATAR after OFFLINE_MODE

On re-reading the diff I figured what Unknwon meant here:
https://github.com/gogits/gogs/pull/3320/files#r73741106

* Remove newlines that weren't there before my intervention

* Fix #3315: Release dont use tag creation date

* Simplify code and apply gofmt

* remove useless block (ctx.Repo.GitRepo.GetTag) on EditReleasePost

* apply gofmt on modified files

Use URL query parameter render=1 to render content in raw mode.

* Add API support for labels.

* Error handling for adding/replacing multiple issue labels

* Revisions to function names and error handling. Use issue.ClearLabels in replace/clear functions

* Additional code cleanup