Add api list, match commands

* 'api list' displays various bits about the API versions available in
  the client and on the servers.
* 'api match' tests the matching bits
* useful in debugging api version-related issues

Depends on the restapi support

Change-Id: I02452f62ee0cd698594bbcf90c0654234d86257a
Merge branch 'oslo-updates' into dt-test
Merge branch 'test-clientmanager' into dt-test
Merge branch 'api-commands' into dt-test