Reap workers in SIGCHLD handler
Reap workers in SIGCHLD handler

This commit tries to minimize the chance of sending a kill signal
to a process that is not a gunicorn worker by reaping children
as soon as the SIGCHLD is received.

Close #371

keakon/gunicorn,mvaled/gunicorn,jamesblunt/gunicorn,ccl0326/gunicorn,z-fork/gunicorn,wong2/gunicorn,ccl0326/gunicorn,zhoucen/gunicorn,elelianghh/gunicorn,tempbottle/gunicorn,GitHublong/gunicorn,prezi/gunicorn,gtrdotmcs/gunicorn,wong2/gunicorn,1stvamp/gunicorn,zhoucen/gunicorn,wong2/gunicorn,malept/gunicorn,ccl0326/gunicorn,mvaled/gunicorn,mvaled/gunicorn,WSDC-NITWarangal/gunicorn,gtrdotmcs/gunicorn,zhoucen/gunicorn,malept/gunicorn,harrisonfeng/gunicorn,jamesblunt/gunicorn,jamesblunt/gunicorn,beni55/gunicorn,ephes/gunicorn,gtrdotmcs/gunicorn,1stvamp/gunicorn,MrKiven/gunicorn,prezi/gunicorn,1stvamp/gunicorn,malept/gunicorn,prezi/gunicorn,tejasmanohar/gunicorn