get_highest_client_server_version should work with any endpoint type:
cinder-api with eventlet, uWSGI, etc.

This patch is based on python-novaclient patch [1]. In a future, we can
deprecate get_highest_client_server_version in flavor of keystoneauth
descovery feature.

[1] Icba858b496855e2ffd71b35168e8057b28236119

Closes-Bug: #1708188
Change-Id: I9acf6dc84c32b25bfe3254eb0f97248736498d32
(cherry picked from commit 19bb7cdf4fcba4a8db540d584d1e03c9276885bb)

--profile argument can be loaded from OS_PROFILE environment variables
to avoid repeating --profile in client commands.

Co-Authored-By: Hieu LE <hieulq@vn.fujitsu.com>
Change-Id: Ia9b469024395327ec0ee082ddaea3234fc3ca5a6

The get_server_version call in cidnerclient/client.py relies on
either finding v 3.x or encountering an exception to revert back
to v 2.0.  It's not clear that this call will always raise if
a non V3 capable Cinder is called, so just to be safe make sure
we return a 2.0 response if there's no V3 reported back.

Change-Id: I3b5fb895cad4b85d5f4ea286fb33f7dd0929e691
Closes-Bug: #1694729

In 'attach' method, documentation vaguely says "Set attachment metadata."
Actually, this method should not be called directly by API users when
attempting to attach a Cinder volume to a Nova instance, else the Nova
and Cinder databases will become inconsistent.

Instead attach function exists solely for use by consumers of Cinder
services such as Nova, so that they can inform Cinder that they're
now using one of Cinder's volumes.

Hence correcting the doc text for attach function.

Change-Id: I34af39f857b6b918de1129f5d210326b3e84d8e1
Closes-Bug: #1611613