The playbooks were running a bunch of common tasks that could be
simplified and unified into a single common_task include. This PR moves
the interface look into a single place and cleans up the duplicate code
within the cinder, neutron, and nova playbooks.
Change-Id: I46f2812670ea17b9ff28ef6f054d82fd6dccc999
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>