OAK-611 - GetJournalCommand does not take path into account

-Added path to NormalizingJsopHandler so it can normalize against any path not just root path.
-Updated GetJournalCommand to normalize diffs
-Added tests in MongoMKGetJournalTest

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1443367 13f79535-47bb-0310-9956-ffa450edef68