Working simple demo scenario

Scenario:
- Simple Tomcat servlet webapp in a AWS Scaling Group
behind AWS Load Balancer
- No DB at the moment

Relies on following Heat fixes:
- fixed stats path in haproxy.cfg
  (heat/engine/resources/loadbalancer.py)
- heat.conf has `loadbalancer_template` configured to point to
  supplied AWS_LoadBalancer.json that
  - uses brebuilt load balancer image
    - does not install packages (they are already installed)
    - allows haproxy under selinux
Add https_proxy parameter to demo template