Added a notebook for Chapter 2.
Modified notebook for Chapter 2.
Add string formatting tutorial
Merge branch 'master' of https://github.com/StewardObservatory/UaNoaoAstroStats
test for pushing to evan
many changes, added bunch of stuff about trees
end of first draft on trees (likely last draft)
fixed some magic function errors
Added to Chapter 2.
Merge branch 'master' of https://github.com/StewardObservatory/UaNoaoAstroStats
Added Chapter3 ipython notebook.
finish chap2