Use mox object from moxstubout fixture

The moxstubout fixture creates a mox object which we can re-use in
tests.

It also ensures verify() is called, which it clearly wasn't in the
case of the qpid tests.

Change-Id: Ibf3326f18b160865012d40a5841b65438262c4df
Merge "Use mox object from moxstubout fixture"