Add ability to specify IAM instance profile

We would like to assign an IAM role to the new instances to let them have access to various resources (like pulling of images from ECR). This adds variable support to allow the profile to be defined, but falls back to empty (which was the default beforehand).

@mikesir - Please resolve the merge conflicts.

added 3 commits

• 461bd17f...144de21d - 2 commits from branch devcom/terraform-modules:master
• bcc76fdf - Add ability to specify IAM instance profile

Compare with previous version

Merge conflicts resolved

LGTM

merged

mentioned in commit b63d942c