Integrate a Dash-based front-end

[mbtown01]

Dash integration for a simple single-page app for configuration/setup

Guiding principles:

• This may be the only web-based integration a user gets (e.g. w/o backend container)
• Should some recent data, but not designed to keep all data over time, just from last boot (need back-end container)

Should expose the following:

• General configuration (things like the setup constants, time zone?? )
• Program (how many programs, when they run, how to respond to price)
• Status/Insights (some simple charts showing price/temperature)
• Controls (maybe even a web-based FROSTI w/ the buttons?!?!).

[mbtown01]

Currently, we're relying on a backing web service to handle all communication between a web frontend and the thermostat logic. With an embedded Dash app, this largely goes away. A simple version of the API can stay around, but we should completely dump it for the time being and replace with Dash.