MISC+DOC: documentation for FeatureAgglomeration

and many cosmetic comments points out in review.
Uniformize max_features semantics
TST add tests with constant features
Update what's news
Remove duplicate what's new
/s/2013/2014: Updated project copyright date
Merge pull request #2857 from eltermann/copyright-updated

/s/2013/2014: Updated project copyright date
Update naive_bayes.rst

Updated the Bernoulli equation for P(x_i|y) to match http://www.inf.ed.ac.uk/teaching/courses/inf2b/learnnotes/inf2b-learn-note07-2up.pdf. The equation currently displayed can't possibly be correct because it gives a 0 probability no matter what value x_i takes.
Merge pull request #2858 from ameasure/patch-1

Update naive_bayes.rst
s/svn/svm
Merge pull request #2859 from eltermann/fixed-typo

s/svn/svm
Merge pull request #2829 from arjoly/maxfeatures-seamantics

[MRG] Uniformize max_features semantics for extra trees and random forest
ENH sparsify and densify methods for CD models
FIX "ValueError: startprob must sum to 1.0" in HMMs

The reason for these error is that the value of self._covars_ is nan.
Adding a minimum denominator 1e-5 will solve these.
MAINT Rename over/underfitting example

Fixes #2834, #2845.
PY3 fixed examples
MAINT comment out unused import in example
MAINT full name for @h10r
FIX error message from trees for large inputs

Fixes #2809 (hopefully).
DOC: minor improvement in comments of an example