use separate thread to monitor process for helix-agent
HELIX-81: org.apache.helix.manager.zk.ZKUtil#isClusterSetup() should not log error
Merge branch 'master' of https://git-wip-us.apache.org/repos/asf/incubator-helix

Conflicts:
	helix-core/src/main/java/org/apache/helix/manager/zk/ZKUtil.java