Positive/negative feature vector looks good.

It doesn't normalize, but adds 1 to pos/neg for each
positive or negative word/reference in the sentence.

This is determined by the liwcutils file. specifically,
in the arrays LiwcDict.pos and LiwcDict.neg
Fixed some pieces of negation

added a more general 'normalize' method
works for + and - categories.
Merge pull request #1 from dcalacci/pos-neg

Pos neg