Delinting
Add a general ActionView that can be used for models which has 'actions'.

An action is considered like recieving a vote, being approved, etc. This
view enables such actions to be invoked by URLs such as <id>/vote and
<id>/approve, from the same view.

Accomplished this by overriding the view dispatch-method to look for
a instance member 'actions' which defines legal actions for the model.
In the URLConf you can then link actions to URLs.
Add a HttpMethodOverride middleware, to allow RESTful cooperation with HTML.

Browsers don't have a specified way to send HTTP DELETE or PUT requests,
so we look for POST requests with a field _http_verb that will override the
real HTTP method for the one specified.
Stop using the horrible Feedback objects, and rather use URL parameters
or template contexts.

This will break existing feedback messages until they've starting using
the new way. Don't care too much about that.
Delinting
Use CBV for the music pages.

Music pages now also use the new way of sending feedback, and uses
the ActionView recently added to the repo for the SongDetailView.

Music also utilizes the _http_verb form field to send HTTP DELETE requests.