Issue #2380 adding whitespace to strings

There are several files mentioned in the summary that I didn't add whitespace for:

examples/applications/plot_out_of_core_classification.py URL
sklearn/cluster/bicluster/spectral.py calling format method
sklearn/datasets/covtype.py URL
sklearn/datasets/twenty_newsgroups.py URL
sklearn/externals/joblib/parallel.py string should be concatenated
sklearn/feature_extraction/tests/test_text.py concatenated unicode characters
sklearn/metrics/metrics.py:114 calling format method
sklearn/tree/tests/test_tree.py calling format method

Let me know if you'd prefer a line break.