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"