Add udev rules files for hiding the docker loopback devices from udisks

This prevents them from showing up on the desktop in a window manager, for example.

@lsm5 was the one who committed this to the Fedora specfile, but he tells me @alexlarsson is really to blame for figuring it through originally; major kudos.  I'm adding it to contrib so everyone can benefit (with a separate file for udisks1 vs udisks2, since they use different environment variables). :+1:

The Fedora guys have tested against udisks2, and I've tested against udisks1 with great success. :+1: