VMware: changing volumeops tests from mox to mock.

Changing unit tests implementation of volumeops to mock. In the process
also moving all these unit tests into a separate class for better
test organization.

Partial-Bug: #1261097
Change-Id: I08b2341b22ed9c8f63930a2c73a9737cbe7ef540
Merge "VMware: changing volumeops tests from mox to mock."