Continues deleting dead code
Moves api to api_v1 in prep for rest framework

In the interests of keeping things ticking over/easily testable, it's
best to preserve this for now.
Replaces tastypie with rest-framework

I've preserved the old API for now, even though the (very minimal)
frontend is tested and working with the new one.  I'll kill tastypie
completely in a separate commit.