Bumped Apache Mesos to latest 1.2.1-rc1.

[tillt]

High Level Description

Bumps Apache Mesos to 1.2.1-rc1 with the addition of

mesosphere/mesos@d39453d
mesosphere/mesos@db85099
mesosphere/mesos@d562795
mesosphere/mesos@f5ba5b0
mesosphere/mesos@5189618
mesosphere/mesos@417be41

Related Issues

Checklist for all PR's

• Included a test which will fail if code is reverted but test is not. If there is no test please explain here:
• Read the DC/OS contributing guidelines
• Followed relevant code rules Rules for Packages and Systemd

Checklist for component/package updates:

If you are changing components or packages in DC/OS (e.g. you are bumping the sha or ref of anything underneath packages), then in addition to the above please also include:

• Change log from the last version integrated (this should be a link to commits for easy verification and review): Apache Mesos commits since DC/OS 1.9.0
• Test Results: https://jenkins.mesosphere.com/service/jenkins/view/Mesos/job/mesos/job/Mesos_CI-build/942/
• Code Coverage (if available): [link to code coverage report]

[d2iq-mergebot]

This repo has @mesosphere-mergebot integration. You can interact with the following commands.

@mesosphere-mergebot label [Work In Progress |Request For Comment |Ready For Review |Holding |Ship It] 
@mesosphere-mergebot bump-ee  

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[tillt]

Downstream test PR https://github.com/mesosphere/dcos-enterprise/pull/883

[adam-mesos]

Could you please update this to 1.2.1-rc1 (only a few commits after fd5d2cf)? If/when the DC/OS CI goes green, you can reference this in an official Mesos 1.2.1 release vote (hint, hint). Thanks!

[adam-mesos]

🚀

[jgehrcke]

🚢

[vinodkone]

LGTM