Implement basic supervised training for v1 nl bot interaction

[mikelax]

Implement a basic NaturalNode classifier to try and understand commands.

Create a sample training set of documents to determine the command to run:

• help
• apod
• rovers photos
• rovers info
• rovers cameras
• list favorites (future)

There should be a default response if no action could be gleamed from the input.
(Future) create full conversation to allow follow up actions. ie. After performing apod, handle "Add to my favorites list".

This should be made modular to allow for switching up the library implementation. Another option would be to use wit.ai Intent Parser.