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? 
Hi, here you changed your previous tutorial which was full brain tracking and copied some parts from the new tutorial from the new tracking tutorial. Now we have two very similar tutorials on tracking with only the model being different.
What if you use full brain tracking here and not seed from the CC? This will have an added value because you show something that it is not available in the other tutorials.