Add a sphinx skeleton

This puts in place an easy way to generate html (or a PDF or whatever) from the source document and also paves the way for auto-generating hosted docs on readthedocs.org.

Also, I would appreciate input on who the "authors" of the document are.  Apparently Sphinx uses this to generate a copyright statement.

I've modified the README slightly to provide a link to readthedocs.

Check out `distributed-array-protocol.readthedocs.org`.