Search for patients

[muuki88]

The first step to export patients is to search for them.

There is a small search service implementation, which you can extend.
It's in the core bundle. Try to use the JPA criteria API, which is a bit verbose,
but easy to use. However you can use plain JPQL/SQL, too.

Hints

Fill the database with some example patients and define some
test cases. Write them down here as a comment, like:

if I search for all boys which are younger than 12 years, I should get xzy