Do refactor for quota command related unit tests, remove
useless code, add new tests to cover '--volume-type' and
'--class' option in "quota set" command and add the
volume quota fake object.
Change-Id: Iaf214740e98db1bfb4c739e810bac1c5ba6e9625
this will better isolate the unit tests from the functional tests.
unfortunately, the "integration" tests had to be lumped into the
"unit" tests since we need the separation in testr.conf
Change-Id: Ifd12198c1f90e4e3c951c73bfa1884ab300d8ded