OAK-1295 - Recovery for missing _lastRev updates (WIP)

Applying patch from Amit Jain

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1583888 13f79535-47bb-0310-9956-ffa450edef68
OAK-1295 - Recovery for missing _lastRev updates (WIP)

Moving common methods to Utils

-- Moving timestampToString to Utils
-- Adding closeIfCloseable to close objects of types closeable.
-- Remove unused methods

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1583889 13f79535-47bb-0310-9956-ffa450edef68