refine build stage with DinD image

.gitlab-ci.yml

@@ -23,6 +23,8 @@ test_client:
     - cd app/client
     - npm install
     - npm run test
+  except:
+    - master # only for now to speed up dev
     
 test_server:
   stage: test
@@ -34,8 +36,15 @@ test_server:
     - cd app/server
     - npm install
     - npm run test
+  except:
+    - master # only for now to speed up dev
 
 build_client:
+  image: docker:19.03.12
+  services:
+    - docker:19.03.12-dind
   stage: build
   script:
     - docker build -f app/client/Dockerfile -t client:v0.0.1 client
+  only: 
+    - master