Entity type changes

I just made some changes to Alex's branch for number and gender stuff and am thus making my own pull request.

Things I added: 
1) I added MentionEntityType to replace EntityType and changes all the other factorie code to account for this.
2) I moved the original rule-based EntityType predictor to the same file as the new one.
3) I tested the code on 10% of the data and confirmed that it gave a very small gain in accuracy:
Before
Test micro B3 79.843 55.875 65.742
Test micro MUC 68.550 47.037 55.792
After 
Test micro B3 80.273 55.793 65.831
Test micro MUC 68.797 46.452 55.459

Note that I think the gain will be bigger for the inference rule where we attach pronouns using rules.

Next step before we merge:
1) add some rules to the entity type predictor for handling pronouns, namely that he,she,him,her, etc. should be PERSON
2) Add a trainer in factorie-nlp-resources for training the MentionEntityTypeLabeller model