build the Dockerimage used in CI

.gitlab-ci.yml

 image: quantumtinkerer/research # until the other image is build
 
-test:
-  script:
-    - py.test --verbose --cov=adaptive --cov-report term --cov-report html adaptive
-  artifacts:
-    paths:
-      - htmlcov
-
-authors check:
-  script:
-    - MISSING_AUTHORS=$(git shortlog -s HEAD | sed -e "s/^[0-9\t ]*//"| xargs -i sh -c 'grep -q "{}" AUTHORS.md || echo "{} missing from authors"')
-    - if [ ! -z "$MISSING_AUTHORS" ]; then { echo $MISSING_AUTHORS; exit 1; }; fi
-  allow_failure: true
-
-check whitespace style:
-  script: ./check_whitespace
-  allow_failure: true
+stages:
+  - prebuild
+  - test
 
 build docker:
+  stage:
+    - prebuild
   image:
     name: gcr.io/kaniko-project/executor:debug
     entrypoint: [""]
@@ -34,3 +23,26 @@ build docker:
       - Dockerfile
       - environment.yml
       - test-requirements.txt
+
+test:
+  stage:
+    - test
+  script:
+    - py.test --verbose --cov=adaptive --cov-report term --cov-report html adaptive
+  artifacts:
+    paths:
+      - htmlcov
+
+authors check:
+  stage:
+    - test
+  script:
+    - MISSING_AUTHORS=$(git shortlog -s HEAD | sed -e "s/^[0-9\t ]*//"| xargs -i sh -c 'grep -q "{}" AUTHORS.md || echo "{} missing from authors"')
+    - if [ ! -z "$MISSING_AUTHORS" ]; then { echo $MISSING_AUTHORS; exit 1; }; fi
+  allow_failure: true
+
+check whitespace style:
+  stage:
+    - test
+  script: ./check_whitespace
+  allow_failure: true