Add missing contributor
Update the contribution instruction
BUG: fix two reST errors.
Merge pull request #33 from rgommers/rest-fixes

BUG: fix two reST errors.
MAINT: typo in README.txt
MAINT: update imports for scikit-learn to use "sklearn".
MAINT: fix plot_GMM example from image processing tutorial.

Note that this plot doesn't seem to be used right now.

Also fix deprecation warning in spectral clustering example.
MAINT: fix a number of small typos and language issues in "tools and workflow".
Add skeletton
Convex vs non convex
Noisy vs non-noisy
Optim dimensionality
constraint optimization
Note on black-box optimization
WIP
Adding forgetten file
1D optimization
Add a demo of gradient descent
Integrate pictures in gradient method
WIP