Issue due date api (#3890)

* Implemented basic api endpoint to manage deadlines

* Fixed checking for permissions

* Updating a deadline from the ui is now entirely done via the api

* cleanup

* Cosmetics

* fixed lint + fmt

* Added swagger model definition for deadline response

* Updated gitea-sdk

* Updated gitea-sdk

* More cleanup

* Generate swagger json

* Merge branch 'master' of https://github.com/go-gitea/gitea into issue-due-date-api

# Conflicts:
#	public/swagger.v1.json

* Fixed permission to update a deadline via api

* Re-added form to change a deadline

* Added client-side validation + not ignore error messages from the api

* Added locale for error message

* Merge branch 'master' of https://github.com/go-gitea/gitea

# Conflicts:
#	models/issue_comment.go

* Proper date validation

* Fixed indention

* moved css to css file

* added documentation for error codes

* after merge cleanup

* Added swagger description

* DO NOTHING BUT TRIGGER THAT F*CKIN CI SO IT PICKS UP THE LATEST COMMIT AS IT SHOULD

* DO NOTHING BUT TRIGGER THAT F*CKIN CI SO IT PICKS UP THE LATEST COMMIT AS IT SHOULD

* regenerated stylesheets

routers/routes/routes.go

@@ -532,8 +532,6 @@ func RegisterRoutes(m *macaron.Macaron) {
 					})
 				})
 				m.Post("/reactions/:action", bindIgnErr(auth.ReactionForm{}), repo.ChangeIssueReaction)
-				m.Post("/deadline/update", reqRepoWriter, bindIgnErr(auth.DeadlineForm{}), repo.UpdateDeadline)
-				m.Post("/deadline/delete", reqRepoWriter, repo.RemoveDeadline)
 			})
 
 			m.Post("/labels", reqRepoWriter, repo.UpdateIssueLabel)