use gitlab to check yml syntax

.gitlab-ci.yml

+stages:
+    - test
+
+before_script:
+    - apt-get update -qq && apt-get install -y -qq ansible-lint
+
+ansible_lint:
+    script:
+        - find . -name *.yml -print0 | xargs -0 ansible-lint
+    tags:
+        - 'librem5'
+    stage: test