SLING-3624 - MBean name and async cron expression added, contributed by Georg Henzler, thanks!

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1614826 13f79535-47bb-0310-9956-ffa450edef68
SLING-3624 - use SlingHealthCheck annotation in AsyncHealthCheckSample

git-svn-id: https://svn.apache.org/repos/asf/sling/trunk@1614829 13f79535-47bb-0310-9956-ffa450edef68