Add link, controller and view for RoI metric

I just added links and the skeleton files for implementing the richness
of information metric detail view.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Put query for sorted scores into repository class

I have refactored the methods for querying the best and worst record for
a certain metric into the repository model class since I believe there
and could be generalized best.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>