Properly invalidate cache for get_*_by_name methods

Use the original name for invalidating the cache on the
get_project_by_name and get_domain_by_name when performing update
operations on the name attributes.

Change-Id: If58a3b0a47501096f9fa9eb9cd7a6057f7b29298
Closes-Bug: #1311142
Merge "Properly invalidate cache for get_*_by_name methods"