Add auth_plugin support to cinderclient

With CINDER_RAX_AUTH being rightfully removed, cinderclient is no longer
compatible with Rackspace/any non-keystone auth. To fix this, I stole
auth_system/auth_plugin from novaclient's implementation.

See https://review.openstack.org/#/c/23820/.

Change-Id: If5f84003f868ef02bb7eb7da67cf62018602e8f0
Closes-Bug: 1280393
When there is no error body return the HTTP reason

Return the response reason when there is no message body to return.

DocImpact
Change-Id: Ia60da4f04b059a13fcbe0059bb42fd77f272d8aa
Closes-Bug: 1248773
Fix usage of v1 and v2 availability zones

Change usage of availability zones in client. V2 client should
use appropriate version of manager of availability zones.

Also change tests of v2 availability zones to test version 2
instead of one more time test v1 availability zones.

Change-Id: Iec3863a105a20f876a303f789cc1edfafa58f4df
Closes-Bug: #1290956
Include the Python 3/3.3 trove classifiers

These are often used by automated tools to check for Python 3 support.

Change-Id: I29fae2c0b80d28a865cc0972272e470da720ca11
Accept deleting multiple snapshots in one shot

In bug 1241941 the delete and force-delete commands were updated to
accept multiple volumes for deleting in the same call. This patch adds
the same behaviour to the snapshot-delete command.

Closes-Bug: #1284540
Change-Id: I5e4bf8641d7fd261fa24b03832bad08007e43c12
Merge "Include the Python 3/3.3 trove classifiers"
Fix malformed encryption-type body in test cases

This change addresses bug #1286261 and fixes two malformed
encryption-type bodies in two test_create test cases.

Change-Id: I308561c1d5a70812889a93922e13194597f670f1
Closes-Bug: #1286261
Merge "Add auth_plugin support to cinderclient"
Merge "Accept deleting multiple snapshots in one shot"
Merge "Fix usage of v1 and v2 availability zones"
Merge "When there is no error body return the HTTP reason"