Added stresstest

Conflicts:
	hazelcast-client/src/test/java/com/hazelcast/client/mapreduce/ClientMapReduceTest.java
	hazelcast-client/src/test/java/com/hazelcast/client/mapreduce/DistributedMapperClientMapReduceTest.java
	hazelcast/src/test/java/com/hazelcast/cluster/ClusterJoinTest.java
	hazelcast/src/test/java/com/hazelcast/mapreduce/MapReduceTest.java