Add domain parameters to user show for Identity V3

Update `user show` for Identity V3 to account for a domain argument,
in doing so, also update `find resource` to be more flexible by
allowing **kwargs.
Also update `group show` and `project show` since they follow the
same logic as a user within a group.

Change-Id: Ib828e4dbeb0bd31164396069ce8a64c873179779
Closes-Bug: #1378165