Port OpenShiftAutoScalaing to yaml

This deploys an identical stack to the original json.

OpenShiftAutoScaling.template has been deleted to reduce
maintenance burden.

Change-Id: Ie2840f65ed0d6f6964b4be71d6b19368e844bac4
Move autoscaling metrics from nodes to broker.

Broker has scripts /etc/heat/notify-scale-up and /etc/heat/notify-scale-down
which will trigger heat autoscaling.

Scaling decisions will be made within the broker itself using its own
platform agnostic scaling scripts:
https://github.com/openshift/openshift-extras/tree/enterprise-1.1/node-manager

This template has successfully scaled up from 1 to 3 nodes, and scaled back
down to 1 by manually executing notify-scale-up and notify-scale-down.

Change-Id: Idb9920438bbe598b610efc8eca5bc158181b74a7