Merge pull request #6 from NelleV/redo_website_yet_again

ENH added the fork me ribbon to the website
add example banner image
Mr. Proper, act 1
Merge branch 'redo_website_yet_again' of github.com:amueller/scikit-learn into website
Merge pull request #7 from glouppe/website

Mr. Proper, act 1
add section, estimator and model links on the frontpage
fix styling of rst links
Banner improvements
add links for examples
Banner style
Banner improvements
Banner style
Merge branch 'redo_website_yet_again' of github.com:amueller/scikit-learn into website
fix css that I just broke with the sphinx links
Merge branch 'redo_website_yet_again' of github.com:amueller/scikit-learn into website
flatten the tutorial / doc structure as proposed by @ogrisel
Boxes on front page
add js for collabsible toc tree in the user guide.
Boxes on front page
minor typo thing