boot.testbus: insserv testbus-agent-kvm if found

Signed-off-by: Olaf Kirch <okir@suse.de>
ni_server_is_running: return value check of ni_pidfile_check was wrong

Signed-off-by: Olaf Kirch <okir@suse.de>
start-kvm-guest: insserv testbus agent on boot

Signed-off-by: Olaf Kirch <okir@suse.de>