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
Add version show command

Change-Id: I76a51d3d6783f46ef2daa0a41626019a880a2a50
Add server image create command

Translation of 'nova image-create', with tests!

Change-Id: I8a833aeff6f291e4774063ed235876eb2ba9c13c
Merge branch 'lib-versions' into dt-test
Merge branch 'api-commands' into dt-test