The CI system needs to have docker 1.11, 1.12, 1.13 and future versions available

[sflxn]

As an engineer on VIC, I should be able to use whichever version of the docker CLI I need for a robot test.
As an engineer on VIC, I should expect at least one of our test suite to at least verify docker commands with all three CLI.

---

Perhaps, have all three version post-pended with their version and "docker" linked to one of them. For example, docker1.11, docker1.12, docker1.13. Docker links to docker1.11 for now.