Currently if someone starts 2 dolphins, the second cannot register
org.freedesktop.FileManager1 meaning and when the first dolphin quits,
no-one has it registered.
It doesn't cause a huge problem right now as we just dbus-activate a new one if
needed, but it means the behaviour is a bit inconsistent and
non-optimal.
DBus has a system to queue names, meaning that as long as any dolphin is
running this name is owned by one of the processes.
Also this patch registers the service after the object which is
technically safer.