Fix pidproxy termination signals behavior

Fix pidproxy problem when receiving a SIGTERM, SIGINT or SIGQUIT, instead of only after relaying the signal it to its child process and terminate, it should wait for the child process termination. This is to avoid supervisor reporting the child process (the one we are interested) in being reported as STOPPED when it is false
Thank you for the advice. I will fix it ;-), Looks like I have suffered from writing too many init scripts