(WIP) Sparse models: S-LASSO and TV-l1

- Supports TV-l1 and S-LASSO priors
- Supports logistic and squared losses
- Has cross validation
- Can automatically select alpha by CV (+ automatic computation of useful alpha ranges for the CV)
- Warning: User must supply l1_ratio
you copied code from different places. Just keep the names when you do this.

At least there is Gael, Gaspard, You, me, certainly Fabian and Michael...

license is important too