[MRG+1] Drop NumPy < 1.8 (#8874)

.travis.yml

benchmarks/bench_plot_nmf.py

doc/developers/performance.rst

doc/whats_new.rst

sklearn/cluster/_k_means.pyx

sklearn/cluster/_k_means_elkan.pyx

sklearn/cluster/dbscan_.py

sklearn/cluster/k_means_.py

sklearn/cross_validation.py

sklearn/datasets/samples_generator.py

sklearn/datasets/svmlight_format.py

sklearn/decomposition/base.py

sklearn/decomposition/factor_analysis.py

sklearn/decomposition/fastica_.py

sklearn/decomposition/nmf.py

sklearn/decomposition/pca.py

sklearn/decomposition/tests/test_nmf.py

sklearn/discriminant_analysis.py

sklearn/ensemble/bagging.py

sklearn/ensemble/forest.py