Refactor module

[jlubken]

Changelog entry

• Refactors module into view and model components.
• Ensures test run on the installed penn_chime module, not the src directory.
• Does not fix dash running as code in src.
• Corrects docs stating that python 2.7 can be used (it cannot)
• Updates docs using the PARAMETERS env variable.
• Documents CLI for developers.

Closes #546 Closes #186 Closes #351 PARAMETERS was previously implemented. Closes #245

[jlubken]

@BrianThomasRoss @dsgit1 @ckoerber @ecsmyth Let's figure out the python packaging for the dash app.

Maybe move the dash app code and app into src/penn_chime/view so it is installed with the penn_chime module. Maybe add the dash app code as part of the penn_chime module and call it from a small script like st_app.py is doing here. Ensure that the templates for i18n are included in the module.

Right now setup is being borrowed to install the dash app's dependencies, but the dash app is not part of the penn_chime module.

At the end of the day, the src directory should not be required to run anything.

Alternatively, pull the dash app into its own project and repo.