Allow region_name to be passed through to nova module
Add comment for region_name to docstring
Merge pull request #7525 from techhat/novafix

Allow region_name to be passed through to nova module
Fix regression in salt-call

This fixes a regression that I inadvertently caused in d749e5a by
always wrapping the return data in a dict. An extra step here in the
Caller class was duplicating this action, causing a traceback when
attempting to increment the result counts for the highstate outputter.