AMBARI-2272. Add unit test to ensure that when MR2 is started it schedules a task for MR2 service check. (Oleksandr Diachenko via smohanty)

git-svn-id: https://svn.apache.org/repos/asf/incubator/ambari/branches/branch-1.4.0@1489544 13f79535-47bb-0310-9956-ffa450edef68