OAK-1341 - DocumentNodeStore: Implement revision garbage collection (WIP)

-- Made maxAge time configurable
-- Registered the JMX bean for version GC
-- Improved debug logging

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1582970 13f79535-47bb-0310-9956-ffa450edef68
OAK-1344 - HierarchicalInvalidator hits query size limit

-- Performing in query in batches
-- Close the cursor properly

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1582971 13f79535-47bb-0310-9956-ffa450edef68