During the upgrade from Queens to Train we currently fail on non-bootstrap
controllers due to a script failure.
This patch does the following:
1. Implements a better bootstrap node check to ensure that the containers
only start on the bootstrap nodes.
2. Improves the db migration check to ensure idempotence if the interim
container is re-run for whatever reason.
Change-Id: I3b610ad2a91ca5deee301c338e4239c25166f41e
5babfe0021