added test for training, featurization and entity extraction in test_extractors.py
added test for training, featurization and entity extraction in test_extractors.py

beeva-fernandocerezal/rasa_nlu,PHLF/rasa_nlu,RasaHQ/rasa_nlu,verloop/rasa_nlu,verloop/rasa_nlu,beeva-fernandocerezal/rasa_nlu,PHLF/rasa_nlu,RasaHQ/rasa_nlu,RasaHQ/rasa_nlu