Use GitLab CI instead of Travis

.gitlab-c.yml

@@ -0,0 +1,8 @@
+image: abaez/luarocks
+
+test:
+  stage: test
+  before_script:
+    - luarocks install --local luacheck
+  script:
+    - $HOME/.luarocks/bin/luacheck .

.travis.yml

@@ -1,12 +0,0 @@
-language: generic
-sudo: false
-addons:
-  apt:
-    packages:
-    - luarocks
-before_install:
-  - luarocks install --local luacheck
-script:
-- $HOME/.luarocks/bin/luacheck --no-color .
-notifications:
-  email: false