Fixes #6531/BZ1117487 - set active menu on $state change.

Ensure the highlighted active menu item is updated on $state
changes.

http://projects.theforeman.org/issues/6531
https://bugzilla.redhat.com/show_bug.cgi?id=1117487

Note that to see the behavior in this PR you must either wait until  https://github.com/theforeman/foreman/pull/1572 is merged or run those changes locally.