Cinder client in Cloud collection

Import cinderclient and initialize it in Cloud class.
Add python-cinderclient in requirements.txt.
Merge remote-tracking branch 'origin/master' into cinder-client
Bump OpenStack client requirements to satisfy cinderclient deps
Add volumes list to resources/ call response
Merge master branch into cinder-client branch
Merge master branch into cinder-client branch
Merge branch 'cinder-client'