Merge pull request #1816 from ndawe/master

Make the setup.py executable
DOC describe SVM probability calibration (and advise against it)
DOC further comments on SVM probabilities
ENH multiclass probability estimates for SGDClassifier

Fixes #1814.
BUG digits grid search was passing cv to the wrong method

GridSearchCV actually ignores this argument, as reported in #1815.
DOC typos in grid search docstrings
ENH Added custom kernels to SpectralClustering

Fixes #1791.