Allow for running tests via testr.

Some projects in openstack are using nose,
some are using testr so attempt to select
the command used by first checking an option
that the component may have set. If that is
not set then attempt to see if the testr
configuration files exists, otherwise select
nose as the backup.

Change-Id: I8e06235f54dded11093d747f161dc4f95b7f6cba
Allow ignoring test failures from the CLI.

It appears that some tests that now run do
not always work correctly, so instead of
stopping immediatly allow users to ignore
failures (so that all tests will run) via
a CLI option.

Change-Id: I08b6f436ed6fb5b117ae039c205245c7c23e18f4
Merge "Allow for running tests via testr."
Merge "Allow ignoring test failures from the CLI."