Minimum Viable Product

This is an open pull request on the `mvp` branch, whose goal is to create a minimum viable product. This is defined as the bare minimum I need to tweet about the site without vigorously deprecating myself, and to feel comfortable showing something to IG offices in meetings.

To kick it off, I did some extreeeemely preliminary planning and sketches, on actual paper.



Even this includes way more than I need. What I need for an MVP is:

* An *adequate* visual style.
* A signup form for the [fortnightly newsletter](https://tinyletter.com/oversight).
* Report listings:
  * Full text search of reports.
  * Per-agency listing of reports.
  * Latest reports.
  * (RSS feeds for all of these.)
* Landing page for report, including extracted text.
* A sitemap.
* SSL certificate.

I consider none of the above optional. There is a lot more that could be done later. And I mean *adequate* with the visual style -- a more thorough design can come later too.