add dependency on vectorz
Factor out the SVD model
Use matrices and kernel function for FunkSVD

- Add biased MF item scorer
- Improve biased MF kernels and model
- Use biased MF model in FunkSVD
Deprecate our vector classes
Make QuantizedRatingPredictor behave like SRP
No longer call the no-op setCache method
Clean up and fix preference domain routing
Use ScoredId for item scoring
Use empty maps in immutable sparse vectors
Implement minimum neighbors for item-item
Add more logging to user-user
Allow multiple scripts for model training
Fix item/user bug in binary rating DAO streaming
Make binary helper classes nonpublic
Implement rating snapshot DAO for model inclusion
Update to support grouplens/grapht#83
Document path for rating snapshot DAO.
Add missing annotations to rating snapshot
Fix default for graph CLI output file
Improve logging