OAK-619 Lock-free MongoMK implementation
- more MongoMK.diff() fixes
- Copied over and adapted MongoMKDiffTest from initial MongoDB based MicroKernel implementation

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1464417 13f79535-47bb-0310-9956-ffa450edef68