Transition from openstack.common.setup to pbr.

Declarative approach to packaging, obviates the need for copying files.
Also, removes the need for setup.py to import files from the nova
module.

./run_tests.sh now ensure's that nova.egg-info/entry_points.txt is up to
date before running tests.

Change-Id: I7b7a18e065a62491ade54fbed5d8400db1d4e6c7
Merge "Transition from openstack.common.setup to pbr."