OAK-2125 - Integrate Lucene logging with Slf4j

The logging integration can now be enabled via OSGi config. Once enable the logging can be controlled via enabling debug logs for 'oak.lucene' category.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1627228 13f79535-47bb-0310-9956-ffa450edef68