kube-aws: add ECR policies to IAMRoleWorker

[spacepluk]

No description provided.

[spacepluk]

Fixes #381

[colhom]

@spacepluk my concern here is that deploying a kube-aws cluster does not imply a need for the instances to have IAM access to ECR images on that AWS account. Maybe this should be configurable, and default to no IAM access?

[valichek]

@spacepluk the list of policies is not full, here is suggested policies http://kubernetes.io/docs/user-guide/images/#using-aws-ec2-container-registry, @colhom kubernetes supports ECR by default. So why not to configure it from the box?

[spacepluk]

Sorry, I completely missed these comments.

@colhom that's a good point but I'd say it makes sense to support it by default.

@valichek thanks, I'll update the patch.

[yuvipanda]

It would be awesome to have this merged :D

[colhom]

Here is a link to the docs for the ECR-K8s integration @valichek was referring to.

Given that this integration exists, I've been convinced. Thanks everyone!