'phd status' should exit with non-zero if daemons are not running.

'phd status' may be invoked by tools (such as puppet) which need to make
automated decisions about whether to start/restart the daemon. To enable this,
'phd status' now exits with 0 if all daemons are running, 1 if no daemons are
running, and 2 if some (but not all) daemons are running.