Added a few statistical distances

Added Chi-square, Bhattacharya, and Intersection distances to compare distributions.
Are you sure about Kullback-Leibler? It may yield negative values if p and q do not sum to 1. 
Wikipedia defines it for probability distributions, and Scipy normalizes the input to sum to 1  (http://docs.scipy.org/doc/scipy-dev/reference/generated/scipy.stats.entropy.html) before computing KL.