make nova functional tests voting

This turns the Nova functional tests voting and adds them to the nova
gate.

Depends-On: Ic276522851fba6d1d95dd1f3bdde1d48935568a3

which lands a no-op tox stub so functional job passes

Change-Id: I3b6a657654f36b374d2fc9902f24d0fde18e93d5
Merge "make nova functional tests voting"