Add ability to configure any catalog driver

Add a catalog_driver parameter which can be used to bypass
the catalog_type parameter and offer finer control over
the catalog driver configuration in Keystone.

Conflicts:
  manifests/init.pp

Closes-bug: #1301592
Change-Id: If062c855c875cf06e192593181898ba0a185a91a
(cherry picked from commit cc0150532c5bc5e6498609132cc97ced3d20985b)