tempest: setup tempest using package

To turn on this method, set
- tempest.setup_method to tempest/rpm
- tempest.use_virtual_env to false
- tempest.checkout_dir to the dir where tempest will be installed
   /usr/share/openstack-tempest

Change-Id: I37235e89b70265dc61b6d5acaf78ddb5e197272f