Add current_app capability to reverse_lazy for all relevant views
Remove current_app from RecordingAPI

For two reasons:

1) RecordingAPI seems to use a different context object, which doesn't expect
current_app, and so any implementation may either a) bue spurious and b) is
more complicated than the rest of current work.

2) This is currently not used in pombola (which is the application which most
uses the current_app and namespacing capabilities)
Add renamed NamespaceMixin everywhere appropriate