Removes fixed ips extension from V3 API

The fixed ip extension was one of the first ported to the V3 API
but a later decision around not supporting nova network in the V3 API
means that this extension is not required for V3. The fixed ip extension
only supports nova network, not neutron and the same functionality
can be accessed directly through neutron.

Also changes some extension tests to use a different extension
for white/black list testing

Partially implements bp nova-v3-api

Change-Id: Ie589170e863ee489661e789c5134ed8349ced279
Merge "Removes fixed ips extension from V3 API"