Replaced a bad allocator CHECK with a TODO.
Removed an invalid CHECK in the allocator.
Updated the master to transform allocations.

Review: https://reviews.apache.org/r/29234
Added protobuf protocol for communicating persisted resources between
master and slave.

Review: https://reviews.apache.org/r/28723
Fixed a compilation issue in GCC 4.6.

Review: https://reviews.apache.org/r/29180
Add slave id to docker container name prefix.
Add option to disable docker containerizer killing orphans
Add executor for docker containerizer
Integrate docker executor into containerizer.
Re-enable docker recover test.
Add docker_mesos_image flag to slave flags.
Add docker_sock to slave flags
Add option to launch docker containers with helper containers.
Fix docker container naming and tests.
Recover docker containers that launched in containers.
Add launch docker containers in containers test.
Launch docker container and log through docker executor.
Install docker as part of the mesos docker build.
Skip docker validation in docker executor.
Change docker executor launch command log level.