Add mgmt API for datastores

Implemented mgmt API calls for create/update datastores/versions.
To access this API call "admin" role is required.
Removed datastores related commands from trove-manage.
Changed response from datastore-list, now regular user can see only
datastores which has atleast one active version.

Change-Id: I01c0ecc276a73fbbc06ec39bfaa1c66f47fc3a9c
Implements: blueprint datastores-mgmt-api