1) they now have their own matching severity constants
2) they both have convenience functions success(), info(), warning() and error()
3) they both have severity_class()
their results, as opposed to having them return their view back
upstream. This is a little more code in every controller, but it's
much less magical and more consistent.
Look up the active_theme and active_admin_theme inside the view
itself, no need to do that in the controllers. This makes view
initialization easier in the controllers.
