If the server (a real one or a service exposed as a server) is
on the same machine as MaxScale, then for performance reasons
a Unix domain socket and not a TCP/IP socket should be used.
This is the base for Smart Router. Review and TODO comments are in the
code. This commit will be squashed several times so don't pay attention to this
specific commit message. I will add and remove TODO's in the code, rather
than save them in git commits. RBCommons will contain the history.