Add python-novaclient to package list

The neutron-l3-agent service fails to start without this package
being installed, due to a Python ImportError:
"No module named novaclient.v1_1.client"

Change-Id: Idc88677b80c93ed2415cedb6de7febc00a975e7f
Closes-Bug: #1307334
Merge "Add python-novaclient to package list"