makefile: update docker images before running tests

Makefile

@@ -1,6 +1,14 @@
 .SILENT :
 .PHONY : test
 
+update-dependencies:
+	docker pull jwilder/docker-gen:latest
+	docker pull nginx:latest
+	docker pull python:3
+	docker pull rancher/socat-docker:latest
+	docker pull appropriate/curl:latest
+	docker pull docker:1.7
+
 test:
 	docker build -t jwilder/nginx-proxy:bats .
 	bats test

circle.yml

@@ -10,12 +10,7 @@ dependencies:
     - sudo add-apt-repository ppa:duggan/bats --yes
     - sudo apt-get update -qq
     - sudo apt-get install -qq bats
-    - docker pull jwilder/docker-gen
-    - docker pull nginx
-    - docker pull python:3
-    - docker pull rancher/socat-docker
-    - docker pull appropriate/curl
-    - docker pull docker:1.7
+    - make update-dependencies
 
 test:
   override: