Add public->private mappings for labs to dnsmasq aliases

This should let labs instances connect to public hostnames
which map to these public IPs, by translating the address
to the private variant in the DNS responses.

In the future, it would be nice to pull this directly
from OpenStack somewhere/somehow.

Change-Id: I685b5cab204e8e319d0663d11fb9872bb81d7b6e