Ability to add *-create-dir service separately

For systemd services, we create 2 services: one for the daemon and one
that creates the run directory under /var/run for the daemon.

For the packaged installs, the daemon service is already provided by the
package, so we need the ability to add just the *-create-dir service.

Some might say that the package should create it's run directory...and
it in fact does. However, we are reconfiguring the services to use
/var/run and the package uses /var/lib. Since /var/run is tmpfs mounted,
we need the *-create-dir services for the packages as well.

Change-Id: If26d9d7da04d3d1d97809db0e21e54dd9f8042ca
Add create-dir service for neutron

The service will ensure /var/run/neutron is created and neutron owned,
which is required by the neutron daemon.

Change-Id: I833b325e24da872e7290fac3d06c04a92980e4c7
Add create-dir service for nova

The service will ensure /var/run/nova is created and nova owned,
which is required by the nova-compute daemon.

Change-Id: I09c2e8734e0c81911ea7cbbc23bff2b1837dacea