webadmin: sort roles in permissions popup

Added sorting of the roles in add permissions popup for
easier use.

This is just the bug fix, cleanup is in a dependent patch

Change-Id: Ifb5fcbebbe39f32193767d0ba6c928e7db4fc6c1
Bug-Url: https://bugzilla.redhat.com/909897
Signed-off-by: Noam Slomianko <nslomian@redhat.com>