JCache Unittests and fixed most of the problems that occured by the tests

One unittest is still failing (com.hazelcast.client.cache.ClientReadWriteThroughJCacheTests#test_loadall_readthrough). I guess I know the problem (the CompletionListener fires after the first node is ready with loading) but no idea how to fix that one.
The difference is that defaultHazelcastInstance is the one passed in to the HazelcastServerCachingProvider or HazelcastClientCachingProvider factory method, whereas the the hazelcastInstance is the one that is automatically created if nothing is configured