Run doctests on travis-ci
Make sure sphinx is installed on travis
Test pypy on travis
Never mind, can't test against pypy due to tkinter bug
Add convenience functions for tokenization

Classifiers use these convenience functions so that text
will be correctly tokenized to sentences before being tokenized
to words
Fix py33 tests
Add maximum entropy classifier
Make sure numpy is installed on travis
Improve NLTKTagger by tokenizing words correctly
Fix word tokenization in NaiveBayesAnalyzer