Add metadata to configure swift

o Adds the required swift metadata (in swift-source.yaml).
o Sets up glance to use the swift backend on the overcloud.
o Sets up glance to use the file backend on the undercloud and seed,
  i.e. maintain the Status quo.

Change-Id: I4a70ffbf9c51f1fea5cfc84d8718d3d30d36b3f2