Merge pull request #2743 from eltermann/doc_fix

Small documentation fix: from CMS to VCS
Merge pull request #2744 from arjoly/test-impurity

TST Gini is equivalent to mse in binary classification
FIX don't put data in source dir in bench_covtype

When running under a tool such as @fabianp's profiler yep,
dirname(__file__) is the location of the tool's __main__.py
instead of the benchmarks directory.

Also, we shipped a tarball containing a large dataset before.
FIX remove confusing BaseEstimator.__str__
Test primal-dual relationship in Ridge.
More robust test for sample_weight in Ridge.
fix: remaining time not currectly computed
Merge pull request #2753 from pprett/gbrt-verbose-remaining-time

fix: remaining time not currectly computed
Fixed documentation typo
OPTIM MSE criterion
OPTIM more optimisation of mse
OPTIM more optimisation of mse

COSMIT
ENH use memset instead of for loop
Typo
Update what's new
Merge pull request #2745 from arjoly/mse-criterion

[MRG] Optimize mean square criterion
Merge pull request #2754 from eltermann/doc-fix-tfidf

Fixed documentation typo
Add mean_absolute_error to scorers.
Merge branch 'master' of https://github.com/scikit-learn/scikit-learn
Fix doctest.