Configure nova_cell1.conf to use placement for reschedules

Nova now calculates alternate hosts in the scheduler and
sends those to the cell for reschedules in case a build on
a given compute node fails.

The cell conductor needs to claim resources against the
alternate hosts in Placement during a reschedule, therefore
it needs to be configured to talk to the placement service.

Part of blueprint return-alternate-hosts

Change-Id: Ie599968d9e7537e551fe6d9deb63a91b256b1e11
2 files changed