OAK-1768: DocumentNodeBuilder.setChildNode() runs OOM with large tree

Merge revision 1627586 from trunk

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1627588 13f79535-47bb-0310-9956-ffa450edef68
OAK-2141: Log timing of background operation

Merge revision 1627590 from trunk

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/branches/1.0@1627591 13f79535-47bb-0310-9956-ffa450edef68