Swagger info corrections (#9441)

* use numbers and not http.Status___ enum

* fix test

* add many missing swagger responses

* code format

* Deletion Sould return 204 ...

* error handling improvements

* if special error type ... then add it to swagger too

* one smal nit

* invalidTopicsError is []string

* valid swagger specification 2.0
 - if you add responses swagger can tell you if you do it right 👍

* use ctx.InternalServerError

* Revert "use numbers and not http.Status___ enum"

This reverts commit b1ff386e24.

* use http.Status* enum everywhere

routers/api/v1/repo/blob.go

@@ -37,6 +37,8 @@ func GetBlob(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/GitBlobResponse"
+	//   "400":
+	//     "$ref": "#/responses/error"
 
 	sha := ctx.Params("sha")
 	if len(sha) == 0 {