FIX make sure laplacian in spectral clustering test is really PSD
DOC: more consistency in metrics docstrings
DOC: More consistency in metrics and clustering metrics docstrings
DOC: more consistency in docstrings for unsup clustering metrics & missing link
DOC: fixed missed details in metrics docstrings
DOC: addressed more inconsistencies in metrics docstrings
zero_one_loss now does normalize on default.
DOC add recall_score to new classification metrics listing
Changed a minus sign to a plus sign in the documentation of n_jobs in some files.
Merge pull request #1577 from ApproximateIdentity/n_jobs-documentation

Changed minus sign to plus sign in the docs of n_jobs in some files.
DOC document gamma in chi2_kernel.
update year in copyright notices
Fresh fixes of grammar errors