* Replace all ctx.Handle with ctx.ServerError or ctx.NotFound

* Change Handle(403) to NotFound, avoid using macaron's NotFound

* Update swagger documentation

Add docs for missing endpoints
Add documentation for request parameters
Make parameter naming consistent
Fix response documentation

* Restore delete comments

* 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

Don't require token when not necessary

* Moved attachaments POST url from /issues/attachments to /attachments

* Implemented attachment upload on release page

* Implemented downloading attachments on the release page

* Added zip and gzip files to default allowed attachments

* Implemented uploading attachments on edit release

* Renamed UploadIssueAttachment to UploadAttachment