Increase JVM memory overhead.

Review: https://reviews.apache.org/r/11130
For cgroups killTasks(): kill, freeze, kill, thaw.

Review: https://reviews.apache.org/r/11131
Don't accept offers on the same host/port.

We'll try to find a port combination that hasn't already been used to
launch a TaskTracker.

Review: https://reviews.apache.org/r/11161/
Call `post-reviews' with --guess-fields argument.

But only do so with the initial creation of the review.

Review: https://reviews.apache.org/r/11159
Ignore errors from post-review.

When updating existing reviews, post-review returns errors erroneously.

Review: https://reviews.apache.org/r/11160
Write Mesos JobTracker stats to state file.

Review: https://reviews.apache.org/r/11165/
Fix post-reviews.py url.

Review:
Pretty-print resource type with parsing error.

Review:
Strip spaces and quotes --resources arg.

Review:
Use string comparison for TaskID.
Fixed synchronization bug when waiting for a process.
Don't log every single completed task.

On large jobs (with many thousands of tasks) this can generate an
unreasonable number of log messages.