Change default test path to unit tests, and support setting
$OS_TEST_PATH to specify a different path (such as functional).
Change-Id: I3c0d597b5e1c43a8cb04ac0fc936e9ad1cdcfbf8
tests/__init__.py implies a package in the global namespace. These
tests are not global python tests, but rather tests for novaclient.
Change-Id: Ifeb8082aa010d15dddc9ae02e35589bc78ad48cc