Feedback from @amueller
Add perceptron loss to plot.
ENH Add support for multioutput metrics
DOC add narrative doc for regression metrics
Update what's new
TST check that ValueError is raised when the number of output differ
ENH add mean absolute error
DOC cosmit alphabet order of classification metric in ref
DOC typo
ENH add multioutput support for dummy estimator
DOC instance attributes + TST: do not record warning
DOC typo
ENH preserve output ndim
ENH: add the squared hinge loss to the SGD loss example
threshold parameter was ignored in SquaredHinge loss.
FIX - nmds now uses the same scaling as previously
Merge pull request #1505 from NelleV/mds

Fixes on the MDS
moved class_prior in NB to __init__
added deprecation warning to fit function
fixed docstring tests