API: allow recursive tree
Related pull request: https://github.com/gitlabhq/gitlabhq/pull/8519. I change a little bit the function to reduce the complexity, and I think a can't do anything to reduce more.
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
Related pull request: https://github.com/gitlabhq/gitlabhq/pull/8519. I change a little bit the function to reduce the complexity, and I think a can't do anything to reduce more.