Replace Java logging by a proper framework for logging

Today, we make use of JUL with serve to our basic needs. Although with the grown of the project, the need to make use of more advanced frameworks like log4j or slf4j are necessary.

After discussing this with mwessend@redhat.com a good idea seems to be to update UPS to use slf4j for logging. We would then be able to choose the logging implementation to be used. This would also allow us to remove AeroGearLogger from the code base.