Add lint to travis

Author: abnegate

.travis.yml

@@ -57,10 +57,13 @@ before_install:
       echo "${DOCKERHUB_PULL_PASSWORD}" | docker login --username "${DOCKERHUB_PULL_USERNAME}" --password-stdin
     fi
 
-
 install:
   - docker --version
   - composer install
 
-script:
-  - vendor/bin/phpunit tests/${SDK}Test.php
+jobs:
+  include:
+    - stage: lint
+      script: composer lint
+    - stage: test
+      script: composer test tests/${SDK}Test.php