fix imports (partial dependence)
fix: california_housing not cal_housing
cosmit
switch axis for 2-way plot; better to compare with above plot
BUG: update joblib to 0.7.0b

Fixes a bug under Windows in the recursive parallel detection
added partial dependence and fetch_california_housing to classes
better documentation
fix links
add partial dependence module
Test expectations.
Test string labels.
Test exceptions.
Cosmit: save one line.
Address @amueller doc comments.
Skip common tests for Dummy*.
Typo :/
Add example in docstring.
Add to references.
Merge pull request #1382 from mblondel/add_intercept

MRG: Add dummy feature utility function
Merge pull request #1373 from mblondel/random_clf

MRG: Dummy estimators