Possible enhancement? Outlier detection
For a project I'm working on I need to identify and remove outliers. After some searching I could not find anything in pandas (or other packages) so I wrote three functions to:
* find outliers using one of z-score, MAD and Quantiles
* plot these outliers on a timer series plot along with an optional trend line.
* replace the outliers with interpolated values.

Are these generally useful enough to warrant adding to pandas? 

This [notebook](https://github.com/Kevin-McIsaac/Nightlife/blob/master/Outlier%20Examples.ipynb) has some exmaples.
