ENH: random reassignements in MiniBatchKMeans

Empty clusters are reassigned to random samples
ENH: fine tuning to the random assignement
DOC: example of dict-learning with KMeans
DOC: improve online KMeans example
DOC: dict learning with kmeans in narrative doc
DOC: fix typo
BUG: check n_clusters == len(cluster_centers_)
PEP8
DOC: change the example to lighter dataset
ENH: more control on reassignment in MiniBachKMeans
DOC: link to example
DOC: add comment
DOC: complete whats_new
TST: random reassignment in MiniBatchKmeans
TST: test verbosity mini_bach_kmeans
ENH: control random_state in MiniBatchKMeans