remove_role bypasses rails callbacks

[EvanWillms]

Roleable.subject.remove_role bypasses the rails callbacks by using delete_all instead of destroy_all. This is causing a problem with our model lifecycle auditing callbacks, as the removal of a role does not trigger appropriate tracking.

[mcrowe]

Yeah, a destoy_all definitely makes more sense there. Pull request are very welcome ;-P ! Else, I'll keep this issue open and get to this when I'm able.