Add option to setup different schedulers on Deis provision

[sgoings]

During the public release planning meeting, @smothiki brought up the idea that being able to choose what scheduler to use with Deis would be a desirable feature for rigger.

The way I would consider implementing that would be:

• add a question that asks this question: "What scheduler would you like to use?" with options:
  • fleet (default)
  • swarm
  • kubernetes
  • mesos
• pick up on this variable (DEIS_SCHEDULER) during the provisioning process (where it makes sense).

[smothiki]

:+1:

[rimusz]

:+1:

[elifarley]

I suggest that comments containing only a reaction icon (like :+1:) should be avoided. Showing the reaction on the original comment takes a lot less screen space and makes it easier to count the number of people with a given reaction.

[bacongobbler]

@elifarley reactions were just introduced last week. Yes we will use them moving forward.

[bacongobbler]

The scheduler tech previews have been removed from the Deis LTS as of https://github.com/deis/deis/pull/4861 (see deis/deis#4860 for context), so there are no more schedulers to choose from other than Fleet for v1. I'd vote that we do not implement this.

[smothiki]

Is there any plan to modify rigger to install deis v2 ?