Add a pandas-sphinx-theme site

[choldgraf]

Currently, the "demo site" for this theme is the Pandas documentation, which is fairly complex and can make it tricky to quickly prototype and demo the docs locally.

What do folks think about creating a lightweight sphinx site that demonstrates this theme, explains its functionality, etc?

Perhaps we should use this issue to brainstorm a set of features that the site would need to demonstrate?

[choldgraf]

This is now here with #54