Distinguish bacula Storage devices based on hostname

We now got 2 Storage Daemons. To support them in bacula we need to
distinguish them by providing them with unique names. Prepend the
hostname in the identifier to achieve this. Amend the director to
actually point to itself for now as in our environment it is also a
Storage Daemon.

Change-Id: Ie8c1b7fe20638de53a1a70c7e0274e39de2b75eb