core: Replace log4j with JUL backend in bll tests

Replaces log4j with java.util.logging backend in bll tests.

Change-Id: I3ebeacfffd6de6766dc43c1d4fdf22d061781797
Bug-Url: https://bugzilla.redhat.com/1109871
Signed-off-by: Martin Perina <mperina@redhat.com>