ContextHandler should be platform agnostic

[Yuffster]

Technically, Cloud™ support would be as simple as disabling the platform-specific checks on ContentHandler. The rest can just be repurposed from

We can still get all the cool instant verification stuff by running each command in a virtualized MotorHandler, should the user want to check for its validity on a personal robot.

Biggest hurdle in this would be changing the data structure for the slots. But once we do that, we also get the ability to not define them in a protocol and then have the protocol class autoassign them, or even prompt the user at a later stage of the process.

Outputting to JSON, after all, is just one of the many things the protocol can do. 😀

[Yuffster]

Check out #26; basically just move the platform-specific ContextHandler exceptions to MotorHandler.