change required start/stop to should start/stop in init

- fixes install error when mysql-server is installed and started after mediator;
- mediator has a mysql reconnection wrapper anyway so this is safe.

debian/mediator.init

@@ -1,8 +1,8 @@
 #! /bin/sh
 ### BEGIN INIT INFO
 # Provides:          mediator
-# Required-Start:    $remote_fs $syslog mysql
-# Required-Stop:     $remote_fs $syslog mysql
+# Should-Start:      $remote_fs $syslog mysql
+# Should-Stop:       $remote_fs $syslog mysql
 # Default-Start:     2 3 4 5
 # Default-Stop:      0 1 6
 # Short-Description: Ngcp Mediator