FIX website layout on small screens

When on small screen:
   - collapse automatically the sidebar
   - doesn't display the search bar
   - doesn't display the github fork me banner
FIX improve display on small device
DOC fix dropdown menu
try to fix the toctree in a semi-meaningful way.
DOC/EXAMPLES fix more documentation errors, deprecated api usages.
EXAMPLES remove non-existing example from doc, don't trigger deprecated interface in enet_path, lasso_path
much better input validation, test that warning is raised on (n_samples, 1) y
FIX: sidebar.js
Move Google javascript near </body>

Conflicts:

	doc/themes/scikit-learn/layout.html
Merge pull request #2293 from amueller/warning_input_shapes

[MRG] Fix tests on master, better input validation.
ENH: add fast_dot function
employ DataConversionWarning
FIX: avoid zero-dvision warnings
FIX: fix test warning
better handling of warning in test
COSMITS