updates to the preprocessor and fixes of testdata
now the words "tweet", "twitter", "rt", "retweet" are also removed in the stopword remover since they are too generic to have any sentiment meaning
added methods to generate the final testing data -> this reads the positive-tweets.csv and negative-tweets.csv and combines them
some fixes to the positive-tweets.csv since the csv writer had some problems..I just generally escaped all tweets that contain ' ..now it works
added some more smilie parsing. added <3 and </3 and some other