Migrate AbstractTestTransaction from TDB.

Add testing of DatasetGraphWithLock using AbstractTestTransaction.
Some tioying up of test organisation.


git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1517160 13f79535-47bb-0310-9956-ffa450edef68
AbstractTestTransaction migrated to jena-arq.

git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1517161 13f79535-47bb-0310-9956-ffa450edef68