Started implementing BERT based target extraction

ADA/.gitignore

ADA/server/agent/agent.py

ADA/server/agent/communicator.py

ADA/server/agent/corenlp_server-32a81a4be283457c.props

ADA/server/agent/dataloader.py

ADA/server/agent/target_extraction/BERT/bert_extractor.py

...server/agent/target_extraction/BERT/modular_bert_model.py

ADA/server/agent/target_extraction/BERT/rel_dataset.py

ADA/server/agent/target_extraction/BERT/relbertnet.py

ADA/server/agent/target_extraction/product.py

ADA/server/agent/target_extraction/target_extractor.py