Publish docs to readthedocs

[mumrah]

Should get some hosted docs setup

[mumrah]

I've imported the project here http://kafka-python.readthedocs.org/en/latest/, but it's just our Markdown files for now.

Once we have some Sphynx docs or something, we should publish them here as well.

[dpkp]

are webhooks configured? http://read-the-docs.readthedocs.org/en/latest/webhooks.html

If so, PR #282 may be able to update RTD automatically.

[dpkp]

docs are updated!