* fix: if Mirrors repo no content is fetched, updated time should not be changed

* fix: sync update time from mirror repo.

* fix: one single session.

* update comment.

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>

* refactor struct's time to remove unnecessary memory usage

* use AsTimePtr simple code

* fix tests

* fix time compare

* fix template on gpg

* use AddDuration instead of Add

* use AfterLoad instead of AfterSet on Structs

* fix the comments on AfterLoad

* fix the comments on action AfterLoad

* Sync releases table with tags on push and for mirrors

* Code style fixes

* Fix api to return only releases

* Optimize release creation and update
Minimize posibility of race conditions

* Fix release lower tag name updating

* handle tag reference update by addionally comparing commit id

* use created & updated instead BeforeInsert & BeforeUpdate

* fix vendor checksum

* only show generated SQL when development mode

* remove extra update column updated_unix

* remove trace config

* Implementation of the feature to view repository size in admin panel
 * Move GetRepoSize to git module
 * Repository.RepoSize -> Repository.Size
 * RepoSize -> Size in template
 * Redo a few bits and pieces
 * Update size when syncing mirror or forking
 * Remove GetRepoSize
 * Changed fatal errors to error message

* Copy migration code from Gogs

* make fmt

* Sync interval specifed as duration string

* Changed mirror interval text

* make fmt

* Add MinInterval for mirror sync

* Use duration internally

* Changed min default to 10m

* make fmt

* Incorrect default

* Removed defaults in MustDuration()

* Add Mirror interval migration

* Default values corrected

* Use transaction during migration

* Change http 500 to page with error message

* Cleanup session.commit()

This change corrects a few logging issues:

 * Standardized formatting errors with '%v'.
 * Standardized failure warning word usage.
 * Corrected an instance of using the standard log library when
   the gitea log library should be used instead.

* Add a process.Manager singleton with process.GetManager()

* Use process.GetManager everywhere

* Fix godoc comments for process module

* Increment process counter id after locking the mutex

- Update import paths from github.com/go-gitea to code.gitea.io
- Fix import path for travis

See https://docs.travis-ci.com/user/languages/go#Go-Import-Path

- Refactor code to use sync.UniqueQueue
- Closes #3509