MAINT docstring --> comments to prevent nose from using doc in verbose mode

sklearn/cluster/tests/test_affinity_propagation.py

sklearn/cluster/tests/test_bicluster.py

sklearn/cluster/tests/test_birch.py

sklearn/cluster/tests/test_dbscan.py

sklearn/cluster/tests/test_hierarchical.py

sklearn/cluster/tests/test_k_means.py

sklearn/cluster/tests/test_mean_shift.py

sklearn/cluster/tests/test_spectral.py

sklearn/covariance/tests/test_covariance.py

sklearn/covariance/tests/test_robust_covariance.py

sklearn/cross_decomposition/tests/test_pls.py

sklearn/decomposition/tests/test_factor_analysis.py

sklearn/decomposition/tests/test_fastica.py

sklearn/decomposition/tests/test_incremental_pca.py

sklearn/decomposition/tests/test_kernel_pca.py

sklearn/decomposition/tests/test_nmf.py

sklearn/decomposition/tests/test_pca.py

sklearn/decomposition/tests/test_sparse_pca.py

sklearn/ensemble/tests/test_bagging.py

sklearn/ensemble/tests/test_base.py