Mesos 0.20 docker integration throws UninitializedMessageException
Merge pull request #249 from cloudysunny14/addedDockerType

Mesos 0.20 docker integration throws UninitializedMessageException
Merge pull request #251 from chengweiv5/master

Fix job deserialization and submit immediate job through REST API
For ZK tests, add small delay.

These tests are flaky and tend to fail randomly, likely due to race
conditions in the ZK election.