Always using domain id to create domain project or user

Add a function to get domain id from a domain name,
and use domain id to create domain project or user.

Change-Id: Ie97c179e62311406201476c0d4c43a731c48908c
Partial-Bug: #1376213
(cherry picked from commit f4998edf938ee83bcecfe8cf4d66822c98bdabb4)