Replaces mox with mock for test_deploy_utils

OpenStack is moving to use mock instead of mox for unit tests
in order to be ready for python 3. This patch changes the
test cases for deployment utils from using mox to mock.

Change-Id: I90bf90310a955a8797dd884e9846f8aeb07524e0
Merge "Replaces mox with mock for test_deploy_utils"