w3a w4a w5a w6a are all using w1a data

[wangqiuoe]

Please see libsvmdata/libsvm.py Line 177-184
LibsvmDataset("w3a_test", "w1a.t", "binary", 300),
LibsvmDataset("w4a", "w1a", "binary", 300),
LibsvmDataset("w4a_test", "w1a.t", "binary", 300),
LibsvmDataset("w5a", "w1a", "binary", 300),
LibsvmDataset("w5a_test", "w1a.t", "binary", 300),
LibsvmDataset("w6a", "w1a", "binary", 300),
LibsvmDataset("w6a_test", "w1a.t", "binary", 300),

[mathurinm]

@wangqiuoe can you send a PR to fix this ?