don't enable Tor DirPort if openvpn is running on port 80 (Bug #6377)

We need to check the openvpn hiera value, which may or may not be set.
If it is not set, then we need to not lookup the $openvpn['ports]'
values or we will get an error because it wont be the correct type.

If we do have it, then $openvpn_ports gets set with the hash, otherwise
it gets set to an empty hash (otherwise puppet will complain when we try
to query the member() later with "member(): Requires array to work
with").

Finally, if it is set to port 80, we don't include the
tor::daemon::directory

Change-Id: Ic366c72e966cae9d611e8fe5aa7ea7943be51241