Add multiple executors

Refactoring / clean up
Adding executors instead of framework messages
Yep, these defaults need to be evaluated to make sure they make sense for the resource requirements.  Right now, the hostname constraint is achieved through resource values (not good).  Will be working on the hostname constraint and will update these values to be sensible defaults.  Documentation in the readme is important for this.  Regarding Node not being capitalized, for some reason it's like that in the code.  I made a note to do that in another pull request as part of the refactoring.