Pin to localstack 0.14.2 (#1236)

Author: GrahamCampbell

Makefile

@@ -4,8 +4,8 @@ initialize: start-docker
 start-docker:
 	docker start async_aws_localstack && exit 0 || \
 	docker start async_aws_localstack-dynamodb && exit 0 || \
-	docker pull localstack/localstack && \
-	docker run -d -p 4575:4566 -e SERVICES=dynamodb -v /var/run/docker.sock:/var/run/docker.sock --name async_aws_localstack-dynamodb localstack/localstack && \
+	docker pull localstack/localstack:0.14.2 && \
+	docker run -d -p 4575:4566 -e SERVICES=dynamodb -v /var/run/docker.sock:/var/run/docker.sock --name async_aws_localstack-dynamodb localstack/localstack:0.14.2 && \
 	docker run --rm --link async_aws_localstack-dynamodb:localstack martin/wait -c localstack:4566
 
 test: initialize