Classify/FeatureVector: Allow for label-attached features, redo FeatureVector factories
*:Get rid of trailing spaces
UserFrequency: Need to cast to long before shifting, even if right operand is long
FeatureVector/Ranker: Merge unigram/ngram features
NewClassify: Separate out ranker/classify command-line params
ParseTweets: Add tweet type for preserving deletion msgs (NEED TO TEST)
Ranker: Add classifier as possible ranker (NOT FINISHED)