* Fix so that user can still fork his own repository to his organizations
* Fix to only use owned organizations
* Add integration test for forking own repository to owned organization
* Make branch deletion URL more like GitHub's, fixes#1397
* Add PR branch deletion integration test
* Do not allow deleting protected branch
* Change http error code to 403 if user has no write rights to repository
* Add check to not panic if forked repository has alrady been deleted