Changed pruning algorithm from removing the top 10% and bottom 10% to removing values outside of 3 standard deviations from the mean.
I asked a statistics buddy if he thought I should divide by `n` or `n-1` and he thinks it should be `n-1`, so updating.
Oops! Added a newline at end of file when you didn't normally have one.
Oops, got the parameters to the callback in  backwards.
Merge pull request #2 from morrisonlevi/std_deviation

Changed pruning algorithm.