Remove tenant round 1 - global options

Change the global auth options to use 'project', leave the original
tenant options in place but silent for compatability with the existing
project CLI auth options.  This is the only compatibility for tenant
usage in this changeover.

Change-Id: I3cce6e552f18822cc9f445ec5f301b0f5d9003f8
Remove tenant round 2 - Identity API

Rename everything in the Identity v2 code including the file and classes.
* role, tenant, user

Change-Id: I0b99c60a24f5875120136d2f216aa3b6bce1c641
Remove tenant round 3 - other commands

Mostly options and help strings:
* image, server, project usage, volume

Change-Id: I788b0660f8c2daacde53c20a72dd1afc60cf5159
Merge "Remove tenant round 1 - global options"
Merge "Remove tenant round 2 - Identity API"
Merge "Remove tenant round 3 - other commands"