Correct the positive and negative persona

[hahuyhoang411]

In the make_dataset, the positive and negative persona looks like it's reverse.

[vgel]

Thanks for this--I'll need to take a deeper look at the tests, since I'm not sure why they're passing with the flipped vector (it's possible I reduced the training examples too much in my attempt to speed up the testsuite, and the vector isn't being trained right...)

[vgel]

Fixed by #34