Feather Core → 0.5

There is an error thrown when running Feather under an adapter other than Mongrel, because the "render_then_call" method used to fire events after the create and update actions within the Admin::Articles controller requires streaming to be supported by the Rack adapter, and currently it seems that this is something that only Mongrel can support. Need to see what it would take to ensure this works under Thin, or if that's not feasible, at least put in a check so that if an adapter that doesn't support streaming is being used, it uses an alternate method to fire those events (it'll probably be slower than the deferred "render_then_call" way though).