Standardize JSON response format

[AHelper]

Different commands have different response formats, some are just plain text, some don't have status codes, they put data in different places. Standardize on:

{
  "status": INT,
  "msg": STR, # Describe the meaning of the status
  "data": [VAL] # Array of optional values, order preserved from request for compound requests.
}

Requests, however, don't need this kind of standardizing.

[AHelper]

Well then, how did I not know about JSON-RPC? This is a good place to start, actually...