[Dev] Web interface for model interaction

[AbrahamSanders]

To start with, this should be a basic single-page application served by Flask, and backed by a FlaskRESTful API to serve the model and track user session state.

The single-page app can be done with any JS UI framework, or just vanilla JS + JQuery.

Primary features:

1. Input textbox for typing commands, dialog utterances, and narrative passages.
2. Output textbox for seeing results of model interaction
3. Support for additional conditioning prompt to precede the active dialog context
4. Support for speech-to-text and text-to-speech via public API

Some inspiration: https://ricsinaruto.github.io/chatbot.html
More inspiration: https://github.com/AbrahamSanders/seq2seq-chatbot/blob/master/seq2seq-chatbot/chat_ui.html

[AbrahamSanders]

First draft of this done in cd13bb8.

Still TODO:

• Support speaker tracking through web UI
• Support command arguments through web UI controls (--show-beams -> checkbox, etc...)
• Get better styling for UI. See: https://bootsnipp.com/tags/chat
• Fix missing punctuation when using speech-to-text
• Give controls to adjust text-to-speech voice