write some ReadTheDocs

[chadwhitacre]

I got a kick out of writing docs for postgres.py and putting them up on RTD:

https://postgres-py.readthedocs.org/en/latest/

Should I start writing dev docs for Gittip and putting them up on RTD? This would replace the README, I think.

[tshepang]

When I saw those excellent docs, are did wonder if Gittip had some. I guess you just answered my question.

[zbynekwinkler]

@whit537 Can we fix building of the docs first? I'd be happy to contribute but the build is not working for me. Autodoc is reporting that it cannot find the gittip modules.

[chadwhitacre]

This is live:

http://gittip.readthedocs.org/en/latest/

Though I'm not sure it will stay there. TBD

@zwn Let's reticket specific issues you're hitting, Mr. Bug Bait. ;-)