Big cleanup and refactor of codebase

This is a big commit, lots of changes have been done here.

First: DAOs have been removed, allowing all code to directly work with the
TableQueries of Slick, since they are always more powerful that whatever
abstraction we can create over them; and, moreover, DAOs were a clean way to
work whenever only simple CRUD operations were involved, but when complex
queries were required, creating DAO methods over them became an ugly fucking
mess. And yes, we lose the abstraction over Slick and make all code dependent
on it, but that is a price that I am willing to take.

Second: Annotators have been split up into the Actor logic and the
Entity-Recognizer/Normalizer logic. The Recognizer/Normalizer has been put into
Service classes, and the Actor logic has been kept in the Annotator classes.
This way we can seamlessly reuse the Service classes to perform normalized
searches (say: earch for "boy", but recover anything that means the same, "homo
sapiens", such as "human" or "person"). Those services were previously placed
into the "utils" package, now they are in the "services" package.

Third: ScalaCheck has been placed as a test dependency, and with that and the
ScalaTest helpers for it, lots of tests have been cleaned up by using
generators and "forAll" checks.