Please describe the problem:
Banshee currently does not run at all if DBus is not running. It would be nice if the DBus-related parts could just simply be disabled if the DBus daemon is not running.

Steps to reproduce:
$ unset DBUS_SESSION_BUS_ADDRESS
$ banshee-1

Actual results:
Unhandled Exception: System.Exception: Unable to open the session message bus.
---> System.ArgumentNullException: Argument cannot be null.
Parameter name: address
  at NDesk.DBus.Bus.Open (System.String address) [0x00000] 
  at NDesk.DBus.Bus.get_Session () [0x00000] 
  --- End of inner exception stack trace ---
  at NDesk.DBus.Bus.get_Session () [0x00000] 
  at Banshee.ServiceStack.DBusConnection.get_ApplicationInstanceAlreadyRunning
() [0x00000] 
  at Booter.Booter.Main () [0x00000] 


Expected results:
This should not cause a crash (chalk one argument in favour of checked exceptions). At the minimum, the dbus-not-running exception should be caught; after that, either Banshee runs without DBus-requiring services, or it should exit cleanly.

Does this happen every time?
Yes

Other information:
See downstream Fedora bug: https://bugzilla.redhat.com/show_bug.cgi?id=487152