Add automated check of conf sample

This adds check_uptodate to run_tests and
tox.ini checks.

This also requires that we add novaclient to the
test-requires, since we try and poke at cinder/compute/nova.

There is another implementation in use to do this that
pulls in openstack.common.config.generator,
(see ceilometer project for a pretty slick impl), however
adding that also pulls in a rather large list of
updates and dependencies that quite frankly Cinder
doesn't need and the ones that we do use break
a number of things in Cinder.

There's also a number of additional options added
to generate_sample that I don't think we need right now.

In the future we'll probably want to go this route
but for now I'd just like to get automated checking
in place.

Change-Id: I91aa4d98f472ad5a3ece7773c75ee76d66adafc0