Pin versions of debian packages

[admont]

• Pin versions of docker-engine, kubelet, kubectl and kubernetes-cni packages.
• Parametrize CNI and Docker package names and versions.
• Cover with unit tests.
• Update documentation.

[scotty-c]

@admont This PR looks good. The only thing we did is actually not add the Docker version as a param. Only that it could allow a user to run a version of Docker that has not been verified by the Kubernetes project. Which could cause support issues on our side. The idea behind hardcoding the version was to allow us to test the version of Docker that works with the widest range of Kubernetes versions. What value would the end user get from adding the Docker version as a param?

[admont]

I see a few reasons. At a moment current versions are: K8s - v1.9.2, Docker - v.1.12.0-x, K8s Puppet module - v1.0.3.

1. Lets say with Puppet module v1.1.0 you are going to upgrade K8s to v1.10.0 and Docker to v.1.13.0-x. But also you fix some bugs and bring new futures. So users would like to have the new version but enterprise users usually prefer to stay with older versions of software - K8s, Docker, CNI, etc.
2. Lets say Debian release a new version of Docker package v.1.12.0-y in some reason. Which doesn't work correctly in users environment. Until Debian release another version of package with fix user most likely prefer to stay with v.1.12.0-x.
3. In some reason user prefer to stay with Docker version v.1.12.0-x but with new K8s version, maybe because of application implementation or CI tools.

[scotty-c]

@admont would you please rebase this PR against master due to merging #82
Thanks in advance

[admont]

Rebase is done

[scotty-c]

@admont I will check this out in the next 24 hours

[admont]

Thanx!
Back to question regarding docker version as a parameter. According K8s documentation the validated docker versions are 1.11.2 to 1.13.1 and 17.03.x. So it is not one binded version. Any way #82 already have docker version as parameter.

[admont]

@scotty-c any news?

[scotty-c]

@admont I will have a look at this one tomorrow. Sorry I have been in transit from Sydney to Belfast

[scotty-c]

@admont Thanks for a great PR

[admont]

Thanx!