Add encryption indicator for volumes

This patch adds support to horizon for a volume encryption
indicator, to display to the user when a volume has an encrypted
volume type. It uses a change made in cinder
(https://review.openstack.org/#/c/72483/) to determine whether
a volume is encrypted or not.

The patch adds an "Encrypted?" column to the project volumes
table, which has the value "Yes" if the volume is encrypted,
and "No" otherwise.  This column is also included in the
admin volumes table.

Implements: blueprint integration-with-cinder-volume-encryption

Change-Id: I2913b96a704d1183606f9fdd970b14a02956e2bb
Adding sahara client api code

This is the code that will interface with the sahara
library.  This is part of the merging of the sahara
dashboard into horizon.
This code was originally from:
https://github.com/openstack/sahara-dashboard

Change-Id: Icdec326e276e1cfeedae6d2fd6047051725f9566
Partial-Implements:  blueprint merge-sahara-dashboard
Co-Authored-By: Nikita Konovalov <nkonovalov@mirantis.com>
Co-Authored-By: Dmitry Mescheryakov <dmescheryakov@mirantis.com>
Merge "Adding sahara client api code"
Merge "Add encryption indicator for volumes"