COSMIT make 'References' bold and minor other fixes.

sklearn/base.py

sklearn/cluster/affinity_propagation_.py

sklearn/cluster/dbscan_.py

sklearn/cluster/mean_shift_.py

sklearn/covariance/outlier_detection.py

sklearn/covariance/robust_covariance.py

sklearn/covariance/shrunk_covariance_.py

sklearn/datasets/descr/boston_house_prices.rst

sklearn/datasets/samples_generator.py

sklearn/decomposition/dict_learning.py

sklearn/decomposition/kernel_pca.py

sklearn/decomposition/pca.py

sklearn/feature_extraction/text.py

sklearn/feature_selection/rfe.py

sklearn/feature_selection/univariate_selection.py

sklearn/gaussian_process/gaussian_process.py

sklearn/grid_search.py

sklearn/linear_model/logistic.py

sklearn/linear_model/ridge.py

sklearn/linear_model/sparse/logistic.py