Force httpd into its own pgroup

Force httpd into its own pgroup to prevent it from TERMing processes
it doesn't own during shutdown.

Resolve bug https://bugzilla.redhat.com/show_bug.cgi?id=1083756
Merge pull request #5157 from ironcladlou/httpd-pgroup-fix

Merged by openshift-bot
Revert "Revert "Card origin_cartridge_133 - Maintain application state across snapshot/restore""

This reverts commit 6fd30130f9e969e43be8c69ba3c5ef577854737f.
This reverts commit 7984305db293bfa7c82cdbc3d69926db0f463487.