Add sentence representation.
Fix a few mistakes in sentence representation.
Add post-processing option.
Remove postaggedTokens, etc.
Remove post methods.
Add wekaConf to root project in Build.scala
Merge pull request #20 from knowitall/sentence

Add a composable Sentence representation
Merge pull request #21 from rbart/fix-weka

Add nlptools-conf-weka to nlptools root project
First pass at a Document representation.
Merge pull request #22 from knowitall/document

First pass at a Document representation.