Add missing security group quota settings to quantum.conf

Fixes bug 1164154

Change-Id: I32d1952fcc11559cc01c0dbde11de558b2a0b1fb
Improve the deprecated message about DEFAULT.root_helper

bug #1166706

Change-Id: Ic90fefefc0c3339cbc876e4402b6d6c5aa841c47
Merge "Add missing security group quota settings to quantum.conf" into stable/grizzly
Merge "Improve the deprecated message about DEFAULT.root_helper" into stable/grizzly