units: turn Wants=shutdown back into Requires=shutdown to avoid removal of jobs due to the impact minimizer

dbus: don't hit an assert if we sent a changed signal for something not in the dbus queue (i.e. because it was deleted before it was fully created

build-sys: drop special name hack for dbus.service since a native service file is now shipped upstream dbus

main: make it possible to run a system daemon along side an aloready running one for testing purposes

units: connect shutdown scripts explicitly with the tty, because native units now default to /dev/null stdout otherwise