PROTON-315: now only skipping MessengerTest.testIncomingQueueBiggerThanWindow if using proton-j.
This required me to distinguish the language of the API from the language of the implementation
(for example proton-jni has a Java interface but a C implementation).

git-svn-id: https://svn.apache.org/repos/asf/qpid/proton/trunk@1485619 13f79535-47bb-0310-9956-ffa450edef68