Add Apache Hama to list of Mesos frameworks.
Change MesosContainerizer::update to not return failure for unknown container.

Review: https://reviews.apache.org/r/22252
post-reviews.py: compatible with git previous to 1.7.2.

The %B formatter introduced in git 1.7.2 while only git 1.7.1
available in RHEL 6.3 release, which is still a widely used release.

Review: https://reviews.apache.org/r/22405
Switched to subprocess.Popen to get stdout streamed from
verify-reviews.

Using Popen instead of check_output means that the output is streamed
to the console. As such, runs that timeout will still include partial
logs enabling us to debug any issues.

Review: https://reviews.apache.org/r/22422
Added healthy field to TaskUpdate.

As a part of the health check story, this patch adds an optional
healthy field to the task update proto.  The semanticist should be
understood as, if the field is absent - no health check has (yet) been
carried out.  If present, it will either encode unhealthy
(healthy=false) or healthy determined by the HealthCheck protobuf in
the command info proto.  This means that multiple TASK_RUNNING updates
can be sent for a task, updating the state of the last health check.

Review: https://reviews.apache.org/r/21499