Member read timestamp shouldn't be updated during heartbeat when its connection is not alive. Cleaned up heart-beater task.
Merge pull request #3029 from mdogan/fix/3.2/heartbeat

Member read timestamp shouldn't be updated during heartbeat when its con...
Fixed remote exception and added unittest to show this is already fixed

Conflicts:
	hazelcast-client/src/test/java/com/hazelcast/client/map/ClientMapLoadAllTest.java
	hazelcast/src/main/java/com/hazelcast/util/ExceptionUtil.java