Async Executor, Manager and Basic Stomp Connectors

Opening this pull request to allow comments from others towards the direction @jlsherrill and myself went with some of the concepts and entities. This is not a fully polished set of commits, there are tests and working examples. We would like to get comments and a window into what we were attempting to do by allowing execution of plans through different means (asynchronous messaging and basic in-process synchronous action). I would not argue this worth merging in it's current state unless all parties are happy with the direction and current state of the code to move forward from.