xboxdrvctl: dbus and env fixes

Changes the shebang line to use python2 instead of python (on modern systems thats python3)

D-Bus -b option was not used, was always using the session bus. Add "auto" arg that tries to find a running daemon in the session bus first, then tries the system bus. Also added "session" and "system" as args.

D-Bus -o option was not used, removed it.