Merge pull request #32 from siculars/master

convenience function for iqr
Specify that it's a naïve classifier

via https://news.ycombinator.com/item?id=5887691
Clean up interquartile range documentation and method
Lower-level accessors for the linear regression line equation.
Add sample skewness by Doron Linder and tests

Also reorganizes tests to make them easier to add and test, and adds
the missing mixin test for browser testing. This needs a new API
section.
Add skewness API docs and fix trailing whitespace
Catch up Contributors list with real contributors. Woot open source!