ENH make minibatch k-means use batches in prediction and computing labels
FIX : explained_variance_ratio_ in RandomizedPCA
update tests
better sparse support
pep8
update what's new
add test with sparse data
address @ogrisel's comments
Merge pull request #2664 from agramfort/fix_randomized_pca

FIX : explained_variance_ratio_ in RandomizedPCA
Merge pull request #2660 from amueller/mbkmeans_compute_labels_fix_new

MRG make minibatch k-means use mini-batches in prediction