Attach to release (#673)

* 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

templates/repo/release/list.tmpl

@@ -59,6 +59,15 @@
 									<li>
 										<a href="{{$.RepoLink}}/archive/{{.TagName}}.tar.gz"><i class="octicon octicon-file-zip"></i> {{$.i18n.Tr "repo.release.source_code"}} (TAR.GZ)</a>
 									</li>
+									{{if .Attachments}}
+									{{range .Attachments}}
+									<li>
+										<a target="_blank" rel="noopener" href="{{AppSubUrl}}/attachments/{{.UUID}}">
+											<span class="ui image octicon octicon-desktop-download" title='{{.Name}}'></span> {{.Name}}
+										</a>
+									</li>
+									{{end}}
+									{{end}}
 								</ul>
 							</div>
 						{{else}}