Channel namespaces need to be a relation to channel requests

[errietta]

We need this so the request is invalidated if it points to a deleted namespace. NB all insert calls in code will have to be updated, as well as text fixtures, and everything will need to be tested thoroughly to make sure errything is still good.

Also after this we'll hopefully be able to show pending requests, that is if it doesn't set the whole project on fire.

As for invalidating requests I'd say to just make a ResultSet that searches only the requests whose namespace isn't deleted and use that, again we'll have to be vewy vewy careful..

KABOOM!!

[errietta]

Resolved as of ab93d0f