OAK-641: Improved benchmark tooling

Improved concurrency tests

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1527256 13f79535-47bb-0310-9956-ffa450edef68
OAK-641: Improved benchmark tooling

Use a more recent Jackrabbit DTD

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1527257 13f79535-47bb-0310-9956-ffa450edef68