Fixed auth on read, update, delete on networks

I think it's safe to say that my previous efforts were hacks at trying to get the right things done. When Nova is the admin, it makes this kind of interaction incredibly difficult, which is why the community built keystone auth in the first place.

Regarding filtering things from the body, I don't think it's ideal, but it IS an acceptable way of doing things, and is in fact something that neutron does at a higher level in the API, albeit with different attribute checks

tl;dr; I can't think of anything better :-)