Update gitlab-ci to run a python2 test

.gitlab-ci.yml

@@ -1,3 +1,11 @@
+python2.7:
+  image: python:2.7-stretch
+  script:
+    - pip install .[test]
+    - pip install .
+    - python -m pytest tests/
+    - pylint --rcfile .pylintrc -E tuir/
+
 python3.6:
   image: python:3.6-stretch
   script: