Get Ubuntu 16.04 working as a base OS for DC/OS
Some of the core requirements for this to be "complete":
- Integration test which starts a cluster on Ubuntu 16.04 and runs integration_test.py
- Start up a cluster, SSH into a master, agent, public_agent and verify all services seem to be up / working properly / came up cleanly / no unexpected error messages
- Test installing services from the universe onto the cluster, verifying they work properly with their test suites.
- Update the CLI/GUI installers to work on Ubuntu (prerequisite installer needs to support ubuntu/apt-get)
- Update installation, pre-requisites documentation as needed