Stop neutron.api relying on base neutron package

There is a weird namespacing issue happening here where the
nova.network.neutronv2.api package is relying on nova.network.neutronv2.
This is backwards from standard design and results in strange sharing
patterns when trying to do clean up.

Change-Id: I5e890c7b72c398e9625e590994d8c2afb9ce8897
Merge "Stop neutron.api relying on base neutron package"