Refactor dispatch.py to avoid code re-use

[deadbits]

In current master branch, the code re-use in Dispatch.py is insane. This has cut the file size down in over half it's size, the workflow makes much more sense, avoid code re-use, and is much easier to follow overall

I've reworked this so all modules and machines go to a single submit function within Dispatch:

• if no argument is required for module, run the module and return results
• attempt to lookup artifact by session ID if provided, otherwise use artifact by name
• verify artifact exists in DB
• populate list of modules to run against artifact (singular if it isnt a machine, multiple if it is)
• send these modules to execute via self.run against the artifact and return results
  • same as before; gets modular pointer via importlib, runs the module and returns results
• call self.save_results
  • to update any existing documents and create any children documents
• create nice JSON data for command line output and return this to omnibus-cli