Stand-alone demo with nice visualizations

This is a pared-down version of the AllenNLP demo intended for use with a single model. The basic idea here is that you copy the code in the demo/ directory, modify two files to create a UI that's specific to your model, then run the demo using npm, hooking up to the AllenNLP simple server.

For a more detailed explanation for how to make this work with your model, see the AllenNLP tutorial on visualizing your model. Here is a very brief outline of the steps involved:

1. Get a simple text in / text out demo of your model running by following the Predictor tutorial in AllenNLP. We'll be using this server as the backend for our demo, so once it works, just keep that server up (it needs to be running on port 8000).
2. Install npm.
3. Copy this repo somewhere.
4. Run npm install and then npm start (from the demo/ directory) and then head to localhost:3000 in a browser to be sure that you see a basic UI that says "Your Model Name".
5. Modify src/ModelInput.jsx to create input fields for your model's inputs and add some example inputs for the dropdown select box. There are TODOs in that file for every place that needs to be modified for your model.
6. Modify src/ModelOutput.jsx to produce whatever visualizations you like with your model's outputs. There are also TODOs in this file showing what places need modification, and some examples for how to visualize attention matrices or plain text output.
7. Try out an example by hitting "Run" - if you've hooked up your inputs and outputs correctly, you should see your simple server get a request (i.e., you should see some output on the console where that server is running), and you should see the results displayed.

As you're doing steps 5 and 6, because we're using npm start to run the server, you should be seeing live updates as you go. npm will recompile your javascript and reload your browser window every time you make a change to your files.