* Fix #3321: commit tag shortener

* Check short commit

* remove debug

* Edit unit tests

* Show 10-char short SHA

* 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

This is an attempt to fix #3089 following the strategy introduced
in d625e41c6c4d40fadbeaf99dd97e77aa0c9085ae, although that strategy
by itself does not seem to be sufficient.

What needs be done is honouring the redirect_url query parameter
from the auth router.

* Do not show the "Sign up for free" button in issue tracker

The "Sign in to comment" link is good enough and will correctly
show or not show the "Sign Up" button link for those not having
an account already.

Fixes #3407 (link to nowhere when registration is disabled)

* Move html from translation to template

* Remove extra space in `{{ .SignInLink }}`.

* add git-daemon-export-ok "support"

* Slight fix to git-daemon-export-ok

* Add error-checking for git-demon-export-ok

* Remove old comments and fixed logging-issues

* Check if git-daemon-export-ok exists or not

* add mirror::GLOBAL_INTERVAL on app.ini

* rename key to DEFAULT_INTERVAL

* add key on default app.ini + move code

* 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