Minor nitpicky fixes

* Rename readme.markdown to README.md (it's just more commonly used.)
* The description mentioned "basic authentication" but I thought that
  was confusing. Also put a link to Chef in there.
* Use readFileSync to read the key in the example to get rid of an
  indentation level.
* Remove the PATCH method. Chef does not support it.
* Add the MIT license to the README.
* Clarify the base URI and body/callback handling if statements.
* Presumptuously add myself to the contributors.
* Remove `npm test` config since there are no tests (yet.)
* Various other minor fixes.

This doesn't change any functionality (other than PATCH, which I'm fairly certain didn't work in the first place), so if approved it could probably go into a 0.2.1 release. Thanks!