Review / Update our Data Model

[scovetta]

Our current data model is super simple, defined here. It's basically a one table for projects and one for all of the metrics. The metrics table is just (key, value), and keys are namespaced (e.g. openssf.bestpractice.raw.foo, example here).

While I don't think we can't continue with this approach, someone should review to see if there's a better approach. This might be more important if/when once we allow users to contribute content (of any sort).