OAK-1578: Configurable size of capped collection used by MongoDiffCache

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1580792 13f79535-47bb-0310-9956-ffa450edef68
OAK-1600: Slow ConcurrentReadIT
- reduce loop count to 10k for now as a workaround

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1580794 13f79535-47bb-0310-9956-ffa450edef68
OAK-301 Document Oak - more query docs

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1580803 13f79535-47bb-0310-9956-ffa450edef68
OAK-1597: QueryStat MBean does not log any query
Enable the query stats

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1580809 13f79535-47bb-0310-9956-ffa450edef68
Merge branch 'upstream-trunk' into OAK-1561