Small doc improvements

These are some incidental improvements I made while converting to `sphinx-better-theme`. They should be reviewed separately.

* `make livehtml` starts a livereload server so when you update the docs locally, your browser refreshes
* "©2009-2013 Yelp *and contributors*"
* Upper left nav breadcrumbs start with "Home" (this will make more sense under `sphinx-better-theme`)
* `docs/requirements.txt` to declare doc-building dependencies (we will revisit this in my next pull request)
* Various formatting fixes