Added permission to run ecs task to build policy (#32)

* Added permission to run ecs task to build policy

Running one-off tasks during build process requires `ecs:RunTask` action. Ability to run such tasks is required for example when applying database migrations. This schema shows how it could be done with CircleCI: https://cdn-images-1.medium.com/max/800/1*eCVCawlDjC_nwIUYdLNxfQ.png

* Update main.tf

* Fixed lint problems

Author: LukGerman

main.tf

@@ -112,6 +112,7 @@ data "aws_iam_policy_document" "permissions" {
       "ecr:InitiateLayerUpload",
       "ecr:PutImage",
       "ecr:UploadLayerPart",
+      "ecs:RunTask",
       "logs:CreateLogGroup",
       "logs:CreateLogStream",
       "logs:PutLogEvents",