Update outlier_detection.rst

Add reference for One-class SVM.
DOC fix opaque background glitch when hovering example icons
FIX better RandomizedPCA sparse deprecation
Merge pull request #3470 from ogrisel/fix-sparse-randomized-pca-deprecation

[MRG] better RandomizedPCA sparse deprecation
DOC: Fix class link

Typos, typos, typos :)
MAINT move log_loss and hinge_loss to the classification metrics
Merge pull request #3472 from arjoly/fix-metrics-division

MAINT move log_loss and hinge_loss to the classification metrics
ENH: Added n_iter_ parameters across all iterative solvers
FIX: Preserve public API by introducing return_n_iter param
TST: Test that after fitting n_iter is greater than 1
Added n_iter attribute to OMP (and CV)
MAINT: Fixed a few docstrings and cosmits
MAINT remove deprecated PCA code
MAINT remove deprecated code from trees and forests
MAINT remove deprecated sklearn.pls module
MAINT remove deprecated code from preprocessing
MAINT remove sklearn.test
COSMIT clean up tests with pyflakes

test_ridge.py contained two duplicate functions.
Implementation of logistic_regression_path.

This is mostly the code from Gael's logistic_cv branch. My work is only some
minor cleanup some added tests and benchmarking.
Take into account @agramfort's comments.

Only cosmetic changes.