API suggestion

[benc-uk]

I found calling the predict API slightly confusing

I had to provide the application/json content type and include my string inside quotes (otherwise it fell over), it feels halfway between a raw POST API and something that is REST based

Suggestion:

1. Leave the content type as application/json and have the API accept the text via small JSON object e.g.

{
  "text": "All my text here"
}

2. Also accept text/plain or unspecified content type, and permit a plain raw string as POST body, e.g.
   curl -X POST -d "Have you seen my hat?" http://localhost:5000/predict

Thoughts?