Allow conflicting services to start when conflict is resolved

These changes add a new svc_block_t type: SVC_BLOCK_CONFLICT so a user
can more clearly see why a run/task/service has not been started by
Finit.  The reason for the block is by default logged, which can be
escaped by using the `nowarn` flag.

Also, when the conflict is resolved, allow the service to start.

With these changes, the system/hotplug.conf should work better and
cause less questions about "strange" log messages.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/api.c

@@ -65,6 +65,7 @@ static int stop(svc_t *svc, void *user_data)
 	service_timeout_cancel(svc);
 	svc_stop(svc);
 	service_step(svc);
+	service_step_all(SVC_TYPE_ANY);
 
 	return 0;
 }
@@ -77,6 +78,7 @@ static int start(svc_t *svc, void *user_data)
 	service_timeout_cancel(svc);
 	svc_start(svc);
 	service_step(svc);
+	service_step_all(SVC_TYPE_ANY);
 
 	return 0;
 }