Sparse Fascicle Model

This is a start on an implementation of the model we describe here: 

http://arxiv.org/abs/1411.0721

The main current issue with this is that this will have a local dependency on scikit-learn, because it uses ElasticNet for the fit. How do people feel about that? 
The mask that you are creating here is not good and for this purpose the tracking at the end doesn't look good.
Please copy the median_otsu parameters from another tutorial.