There is no more AudioFingerprintingUnit. I've done quite of a re-factoring, simplifying the fluent interface for fingerprinting and querying. Now everything is build across Builder and Command patterns. 

This was done as a preparation step towards an independent and clean interface for ModelService (aka backend), which is going to have multiple implementations: SqlModelService, InMemory, NoSql (either Mongo or Cassandra), etc. Please delete this file.