Leadership calendar PDF

Still needs style tweaks to the PDF but figured I can tackle that next sprint.
Also this needs the following ENV vars set:

```
PDF_URL_RULE_1=/the-bureau/leadership-calendar/pdf/
PDF_RENDER_URL_1=DEMO-DOMAIN/the-bureau/leadership-calendar/print/
```
Gotcha. I propose we shift the approach on this a little. I think we should stick with the convention (at least, it seems to be a widely-adopted convention, from what I've seen) of having `base.html`contain the `<html>` to `</html>` page skeleton.

If we restore everything to `base.html` and add in your new `{% block body scoped %}`, then we can create new `screen.html` and `print.html` templates that extend `base.html`, and instead of having our major templates extend `base, they extend `screen` or `print`.

What do you think?