devstackgaterc for controlling fullstack config
devstackgaterc for controlling fullstack config

Add devstackgaterc - instead of updating project-config for each
configuration change we want in devstack, we could update the
devstackgaterc file

Change-Id: I287b9339a2b5656c25bc91b8bcd43a2d242f5a23

openstack/smaug,openstack/smaug