OAK-961 Parametrise tests to run against all Microkernel backends
Parametrise ObservationJcrTest and QueryJcrTest. Like the tck tests these tests now also execute against the SegmentMK and the MongoMK unless no MongoDB is running locally.

git-svn-id: https://svn.apache.org/repos/asf/jackrabbit/oak/trunk@1515804 13f79535-47bb-0310-9956-ffa450edef68