inference: accept path or dict

[djkapner]

the API layer reads and validates arguments. It currently must then write those to disk so the inference class can get a path as an argument. It would be preferable to send the args to the inference class in memory.

Tasks:

• [ ] change inference class to accept either a path to a json, or a dictionary.
• [ ] change the inference API layer to pass a dictionary.

[jeromelecoq]

We just deployed the CLI at a broader scale to fix this. My plan is to transition all users to the CLI so that we can remove this behavior without impacting anyone.