Add unit tests for the existing predefined scenarios

The following discussion from !41 (merged) should be addressed:

• @josephburnett started a discussion: (+2 comments)

  @tmaczukin I remember you were hoping to merge this week. So that you could have a stable release branch off of which to work. Do you have any updates on this?

Steps to complete:

• MR: scenarios/aws/linux/docker-autoscaler-default 👉 Add AWS EC2 Docker autoscaler unit test for def... (!222 - merged) • Davis Bickford • 17.11
• MR: scenarios/google/gke/operator 👉 Add unit tests for gke operator scenario (!246 - merged) • Davis Bickford • 17.11
• MR: scenarios/google/linux/docker-autoscaler-default 👉 Add Google Linux Docker autoscaler unit test fo... (!223 - merged) • Davis Bickford • 17.11