Use region_name in service catalog

Using attr and filter is no longer necessary. We provide a region_name
filter directly that works with both v2 and v3 service catalogs.

Change-Id: I67b50fcaa5e4df5c2bb7b2966b5ef2040e6286e7
Remove "OPTIONAL:" from optional argument help text

All arguments starting with '--' are optional and listed
under the 'Optional arguments:' header by argparse.  Remove
the extra note shown for each argument.

Change-Id: Ic361a3bdbd1f1669458e16b99995f0f108400699
Updated from global requirements

Change-Id: I46186b2dc8d0e01bea982b4cab6347bcd86bf558
Merge "Remove "OPTIONAL:" from optional argument help text"
Remove deprecated command-line args

Some command-line args were deprecated in Diablo and slated for removal
in Folsom. They're being removed in Juno instead.

Change-Id: I02339ba08c997fecca5a6639382360962e668bfd
Merge "Use region_name in service catalog"
Merge "Remove deprecated command-line args"
Fix version discovery and auth_plugins

V3Client support added version discovery and session supports. Most
of the external auth system doesn't support this. This fix bypasses
version discovery if the idenity service doesn't support that. Session
is used only if  no external auth plugin is used

Change-Id: Ia84a2ad45940d35c5ef740727f5f7477c72ea9d4
Closes-Bug: #1333961