Data science 20141007 rc

First pass at the data science exercise.

-simple json file loading
-Dataset contains all results from file, helper methods for calculations, uses ABAnalyzer class to calculate probability
-main.rb used to display results (sample size, conversions, percentages with error ranges, and confidence level)
1.96 looks like a great opportunity to use a constant or something configurable at a higher place (even if just at the top of this file)