Adding support for https://github.com/gitlabhq/gitlabhq/pull/4363

Assuming this pull request (https://github.com/gitlabhq/gitlabhq/pull/4363)
is accepted - this commit will support new the api methods.

This PR shouldn't be accepted until the change is merged in, and of course if there is anything to do regarding versioning (As I'm assuming the change wouldn't be pushed until 5.x or 6.0 you may want to build the gem as a certain version.)