AWS LoadBalancer resource does not process Protocol property

[Pavlo Shchelokovskyy]

AWS LoadBalancer resource has 'Protocol' property for listeners, that is required and accepts either 'HTTP' or 'TCP' value [1]. In fact though, this property is not used anywhere outside resource property schema declaration, and building haproxy config is hardcoded for settings better suited for HTTP.

Although I understand that this property is required for API compatibility with actual AWS, we should at least document this caveat better, or indeed implement corresponding logic.

[1] https://github.com/openstack/heat/blob/master/heat/engine/resources/loadbalancer.py#L359-L366