OAK-967: Run parameterized tests in parallel

The parallel setup would result in concurrent initialization
of and related warnings from the logging system. By adding an
explicit logger already in this class, we can force the logging
system to auto-initialize itself already before the concurrent
test execution starts.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1522940 13f79535-47bb-0310-9956-ffa450edef68