add support for Mesos masters running with --no-root_submissions, see AURORA-311

Review board entry for https://issues.apache.org/jira/browse/AURORA-311

Testing Done:
Tested successfully on internal cluster with version 0.5.1. Aurora was able
to connect to a mesos master that was running with --no-root_submissions and
was able to schedule tasks with a role of EXECUTOR_USER that then were
running as the specified executor user.

Bugs closed: AURORA-311

Reviewed at https://reviews.apache.org/r/23471/
Fix bug in handling of pystachio bindings.

Also, add new unit test to prevent regressions.

Bugs closed: aurora-659

Reviewed at https://reviews.apache.org/r/24953/
Add command output tests for "job create", "job killall", "job kill"

Add tests to ensure that IO behavior of client commands is correct.

Improve IO behavior in the IO client, so that users get more information.
Formorely, many commands succeeded silently, when it would be more helpful to actually tell the user that you did something. (This shouldn't affect scripting, because in these commands, the only result that's needed by a scripter is succeess/failure, which is carried by the exit code.)

Bugs closed: aurora-645

Reviewed at https://reviews.apache.org/r/24852/
Fixing checkstyle build break introduced in
https://issues.apache.org/jira/browse/AURORA-311

Bugs closed: AURORA-311

Reviewed at https://reviews.apache.org/r/24982/
Refactoring maintenance commands to host_ prefix
and converting perform_maintenance_hosts into host_drain.

Bugs closed: AURORA-43

Reviewed at https://reviews.apache.org/r/24871/
Fix default logger in command runner.

Bugs closed: AURORA-670

Reviewed at https://reviews.apache.org/r/25108/
Adding pause/resume/abort client APIs.

Bugs closed: AURORA-615

Reviewed at https://reviews.apache.org/r/25159/
Fixing race in task secondary index.

Bugs closed: AURORA-667

Reviewed at https://reviews.apache.org/r/25133/
Adding support for a pre-update quota check.

Bugs closed: AURORA-649

Reviewed at https://reviews.apache.org/r/24995/
Add a separate main class that runs the scheduler in local mode.

Bugs closed: AURORA-658

Reviewed at https://reviews.apache.org/r/25257/
Make config-file an optional parameter for "job restart."

Bugs closed: aurora-673

Reviewed at https://reviews.apache.org/r/25297/
Add a state machine to react to job update status changes.

Bugs closed: AURORA-613

Reviewed at https://reviews.apache.org/r/25300/
Checking for cron jobs in startJobUpdate()

Reviewed at https://reviews.apache.org/r/25311/
Adding "get" job update client APIs.

Bugs closed: AURORA-615

Reviewed at https://reviews.apache.org/r/25204/
Increment Mesos version to 0.20.0

Bugs closed: AURORA-674

Reviewed at https://reviews.apache.org/r/25208/
Fix aurora run in end to end tests.

Testing Done:
$ bash src/test/sh/org/apache/aurora/e2e/test_end_to_end.sh

Unfortunately the v2 client end to end tests are currently broken
(filed https://issues.apache.org/jira/browse/AURORA-677), but I
verified that the test for aurora task run works in that script
as well.

Bugs closed: AURORA-676

Reviewed at https://reviews.apache.org/r/25206/
Fix output formatting error in "job status".

Bugs closed: aurora-672

Reviewed at https://reviews.apache.org/r/25309/
Upgrade to latest in jetty 7.x series.

Bugs closed: AURORA-679

Reviewed at https://reviews.apache.org/r/25285/
Specify required vagrant version in Vagrantfile.

Bugs closed: AURORA-683

Reviewed at https://reviews.apache.org/r/25346/
Fix build failure caused by timezone issue in tests.

Timestamps in pretty-printed job status use the local timezone.
Jenkins machines use GMT as their local time; so the time printed
on jenkins differs from times printed elsewhere.

This fix fuzzes out the time in the timestamps, so that it doesn't matter
where the test is run.

Bugs closed: aurora-684

Reviewed at https://reviews.apache.org/r/25350/