COOPR-554 change the zk implementation of queue group to watch
the zk node for changes so that queue additions and deletions in
one process are reflected in the other.
Merge branch 'develop' of github.com:caskdata/coopr into feature/COOPR-554-fix-ha-queues

Conflicts:
	coopr-server/src/main/java/co/cask/coopr/runtime/ServerMain.java
	coopr-server/src/test/java/co/cask/coopr/http/ServiceTestBase.java
Merge pull request #753 from caskdata/feature/COOPR-554-fix-ha-queues

COOPR-554 change the zk implementation of queue group to watch