Update circle.yml to use Makefile

Use the makefile to build & tag the image, as well as run tests in it.

Author: Will Fleming

Diff for: circle.yml

@@ -9,13 +9,11 @@ machine:
     CODECLIMATE_DOCKER_REGISTRY_EMAIL: ops@codeclimate.com
 
 dependencies:
-  override:
-    - docker build -t=$PRIVATE_REGISTRY/$CIRCLE_PROJECT_REPONAME:b$CIRCLE_BUILD_NUM .
-    - npm install
+  override: #no-op
 
 test:
   override:
-    - npm test
+    - IMAGE_NAME="$PRIVATE_REGISTRY/$CIRCLE_PROJECT_REPONAME:b$CIRCLE_BUILD_NUM" make test
 
 deployment:
   registry: