common/attributes: Add a helper function for seeing if this set of attributes is a superset of that set of attributes
genericize to isSuperset and isSubset
Fixed the build error in routing tests.

Review: https://reviews.apache.org/r/24902
Fixed MesosContainerizer to reject tasks that have ContainerInfo set.

Review: https://reviews.apache.org/r/25033
Log the uid and pid when receiving a SIGTERM.

Review: https://reviews.apache.org/r/24700
Refactored the JSON output streaming.

Review: https://reviews.apache.org/r/24877
Adjustments for new JSON streaming.

Review: https://reviews.apache.org/r/25053
Fix brokenness...