Teach cosmos to wait for leader.mesos
Teach cosmos to wait for leader.mesos

```
Sep 06 04:29:30 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:30.987 INFO  [main] c.t.finagle.tracing.DefaultTracer$ - Tracer: com.twitter.finagle.zipkin.thrift.SamplingTracer
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.035 WARN  [UnboundedFuturePool-1] com.twitter.finagle.InetResolver - Failed to resolve master.mesos. Error java.net.UnknownHostException: master.mesos: unknown
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.035 WARN  [UnboundedFuturePool-2] com.twitter.finagle.InetResolver - Failed to resolve master.mesos. Error java.net.UnknownHostException: master.mesos
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.043 WARN  [UnboundedFuturePool-1] com.twitter.finagle.InetResolver - Resolution failed for all hosts
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.046 WARN  [UnboundedFuturePool-2] com.twitter.finagle.InetResolver - Resolution failed for all hosts
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.050 WARN  [UnboundedFuturePool-3] com.twitter.finagle.InetResolver - Failed to resolve leader.mesos. Error java.net.UnknownHostException: leader.mesos: unknown
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.051 WARN  [UnboundedFuturePool-3] com.twitter.finagle.InetResolver - Resolution failed for all hosts
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.051 INFO  [UnboundedFuturePool-1] com.twitter.finagle - adminRouter: name resolution is negative (local dtab: Dtab())
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.051 INFO  [UnboundedFuturePool-2] com.twitter.finagle - marathon: name resolution is negative (local dtab: Dtab())
Sep 06 04:29:31 ip-10-0-4-168.us-west-2.compute.internal java[1787]: 04:29:31.054 INFO  [UnboundedFuturePool-3] com.twitter.finagle - mesos: name resolution is negative (local dtab: Dtab())
```

branden/dcos,xinxian0458/dcos,vishnu2kmohan/dcos,darkonie/dcos,GoelDeepak/dcos,branden/dcos,vishnu2kmohan/dcos,mnaboka/dcos,branden/dcos,mnaboka/dcos,asridharan/dcos,mnaboka/dcos,mesosphere-mergebot/dcos,vishnu2kmohan/dcos,mnaboka/dcos,mesosphere-mergebot/mergebot-test-dcos,darkonie/dcos,mesosphere-mergebot/dcos,darkonie/dcos,lingmann/dcos,lingmann/dcos,surdy/dcos,kensipe/dcos,mellenburg/dcos,amitaekbote/dcos,mesosphere-mergebot/dcos,BenWhitehead/dcos,darkonie/dcos,jeid64/dcos,lingmann/dcos,xinxian0458/dcos,asridharan/dcos,darkonie/dcos,BenWhitehead/dcos,mesosphere-mergebot/dcos,dcos/dcos,mellenburg/dcos,dcos/dcos,mellenburg/dcos,jeid64/dcos,lingmann/dcos,mellenburg/dcos,mesosphere-mergebot/mergebot-test-dcos,asridharan/dcos,BenWhitehead/dcos,xinxian0458/dcos,vishnu2kmohan/dcos,GoelDeepak/dcos,jeid64/dcos,mnaboka/dcos,surdy/dcos,BenWhitehead/dcos,amitaekbote/dcos,amitaekbote/dcos,asridharan/dcos,amitaekbote/dcos,branden/dcos,mesosphere-mergebot/mergebot-test-dcos,GoelDeepak/dcos,kensipe/dcos,jeid64/dcos,kensipe/dcos,kensipe/dcos,GoelDeepak/dcos,surdy/dcos,xinxian0458/dcos,surdy/dcos,dcos/dcos,dcos/dcos,dcos/dcos,mesosphere-mergebot/mergebot-test-dcos