fix cut-and-paste error; SIGUSR2 should add a minion

Author: joeshaw

pyres/horde.py

@@ -219,7 +219,7 @@ def register_signal_handlers(self):
         signal.signal(signal.SIGINT, self.schedule_shutdown)
         signal.signal(signal.SIGQUIT, self.schedule_shutdown)
         signal.signal(signal.SIGUSR1, self.kill_child)
-        signal.signal(signal.SIGUSR1, self.add_child)
+        signal.signal(signal.SIGUSR2, self.add_child)
 
     def _schedule_shutdown(self):
         self.schedule_shutdown(None, None)