make better sphinx templates

[Will Kahn-Greene]

We use Sphinx to build the documentation. We need a better set of
templates so:


1. our docs look like our docs
2. our docs don't look like everyone else's docs
3. we can tweak the look-and-feel to make our docs more readable
   and usable

We should at least do a first pass of this for 0.0.1.

The templates are Jinja2 templates. It's possible we might be fine
with just adjusting the CSS.