Convert RBD unit tests to use mock instead of mox

Change-Id: If32e14a8f5ff180b6c0ff46797bcb81b21f805f1
Closes-bug: 1261864
Merge "Convert RBD unit tests to use mock instead of mox"
(Test commit) Change README to reflect Jio's fork of Cinder

Change-Id: I3f26c0a736e63725aec24ca2fa12c707b8e6460f