Merge branch 'ci_cleanup' into 'master'

Gitlab CI: added docker build cleanup job

See merge request !5

.gitlab-ci.yml

 before_script:
-  - docker info
+    - docker info
+
+stages:
+    - build
+    - build_cleanup
 
 build_test:
-  script:
-    - docker build -t argonneeic/base:$CI_COMMIT_REF_NAME --build-arg BUILD_THREADS=20 .
-  except:
-    - master
+    stage: build
+    script:
+        - docker build -t argonneeic/base:$CI_COMMIT_REF_NAME --build-arg BUILD_THREADS=20 .
+    except:
+        - master
 
 build_latest:
-  script:
-    - docker build -t argonneeic/base --build-arg BUILD_THREADS=20 .
-  only:
-    - master
+    stage: build
+    script:
+        - docker build -t argonneeic/base --build-arg BUILD_THREADS=20 .
+    only:
+        - master
+
+cleanup_docker:
+    stage: build_cleanup
+    script:
+        - docker rm $(docker ps -qa --no-trunc --filter "status=exited")
+    when: on_failure