LBaaS - External Load Balancing/Internal Load Balancing via abstraction

[EarthmanT]

As @funkyHat indicated, we currently support Load Balancing via these configurations.

These are sufficient for external load balancing, however, since there are some post-setup steps to support internal load balancer, as indicated here, in particular the remove external IP step, we thought we would support an abstraction above our supported types and call it LBaaS, that will support both internal and external scenarios.

This will also enable us to support several types of LBs from a single node type.

@isaac-s, please comment.

[isaac-s]

@EarthmanT AFAIK, providing abstraction over types of resources runs counter to Cloudify's "spirit", when talking about node type abstraction (providing the abstraction in the actual plugin code, having common code implement both internal/external, is OK — as it is an implementation detail that is hidden from the user). Why would we make an exception in this case, while we have consistently refused to abstract node types in the past?