Centralize naming the testing support files root directory location.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1531022 13f79535-47bb-0310-9956-ffa450edef68


git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1531048 13f79535-47bb-0310-9956-ffa450edef68
Merge remote-tracking branch: upstream/trunk