feat(tox): add basic .gitlab-ci.yml

.gitlab-ci.yml

+image: python:3.7
+
+before_script:
+  - pip install tox
+
+check-manifest:
+  script: tox -e check-manifest
+
+flake8:
+  script: tox -e flake8
+
+py27:
+  script: tox -e py27
+
+py3:
+  script: tox -e py3

MANIFEST.in

@@ -11,3 +11,4 @@ recursive-include test/data bootstrap_cubes *.py
 
 prune debian
 exclude *.spec
+exclude .gitlab-ci.yml