Define and document the structure of the flask app for the grouping milestone

[dschonholtz]

I want to make sure I spend the proper amount of time structuring this application.
I will likely need to serve a separate page that is similar to the existing testing_interface page that shows the groupings.
I will also need models
1 that fetches the data from the github api.
2 that does the actual grouping by feature

What this ticket is, is writing down exactly what that structure is and how the grouping will be done in the wiki.