Add searchDepth when getClusterInfo called.

Without searchDepth, getClusterInfo shows every volume and
snapshot. It's an unused information and takes very long time.

Change-Id: Id590e3023f4446f01b965baf4e8ac61980101067
Closes-Bug: 1276388
Merge "Add searchDepth when getClusterInfo called."
(Test commit) Change README to reflect Jio's fork of Cinder

Change-Id: I3f26c0a736e63725aec24ca2fa12c707b8e6460f