Generate swagger json (#1402)

- Generate swagger.json into public/
- Add swagger-ui auto-installation
- Add footer link to local swagger-ui
- Add /swagger url for using app url.
- Fix Swagger-UI version via git tag

routers/api/v1/misc/version.go

@@ -12,5 +12,17 @@ import (
 
 // Version shows the version of the Gitea server
 func Version(ctx *context.APIContext) {
+	// swagger:route GET /version getVersion
+	//
+	// Return Gitea running version.
+	//
+	// This show current running Gitea application version.
+	//
+	//     Produces:
+	//     - application/json
+	//
+	//     Responses:
+	//       200: ServerVersion
+	
 	ctx.JSON(200, &gitea.ServerVersion{Version: setting.AppVer})
 }