A minimal cells v2 setup is required in Ocata, which includes the
following databases:
1. An API database (named nova_api)
2. A special cell0 database (named cell0)
3. A "cell1" database (named nova - we're using the nova db as cell1)
The order of nova-manage commands is also updated in this commit.
The 'nova-manage api_db sync' must occur first because 'nova-manage
cell_v2' commands use the API database. 'nova-manage db sync' must
then be run after the 'nova-manage cell_v2' commands.
Finally, 'nova-manage cell_v2 discover_hosts' must be run whenever a
new compute node is introduced to add the host to cell1.
This commit includes a sync of charm-helpers to pick up AMQPContext
updates for transport_url.
Change-Id: Ia6f36ca8a360dc8490e9f41b62d499fa4d73d0b9