Remove log() expression from x axis label
Add pseudocode for making the x-axis symmetrical

refs #5
Make x-axis symmetrical

Fixes #5
Make x-axis tick labels fractions instead of exponents

Fixes #4
Clean data to create 34 x 2 dataframe
Add 2014 national summary data

http://media.collegeboard.com/digitalServices/pdf/research/2014/National
_Summary.xlsx

downloaded from
http://research.collegeboard.org/programs/ap/data/participation/ap-2014
Ignore ipython notebook checkpoint files
Add USA Today graphic
Add iPython Notebook
Merge pull request #6 from briandk/ipython-notebook-analysis

Ipython notebook analysis