OAK-377 Data store garbage collection (test cases for external sort)

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1576678 13f79535-47bb-0310-9956-ffa450edef68
OAK-98 Source code formatting, code conventions, Javadocs

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1576679 13f79535-47bb-0310-9956-ffa450edef68