Add ceilometer to the sys.path before the nova starts

The setup.py setup develop adds package to the
 /usr/lib/python2.7/site-packages/easy-install.pth.

The nova uses the ceilometer.compute.nova_notifier, so it must be
in the path before the nova started.

Change-Id: I80ed5e5611278e75afa7ab7f8fb91417897d423f
Merge "Add ceilometer to the sys.path before the nova starts"