Add test Travis configuration

.travis.yml

@@ -0,0 +1,25 @@
+dist: trusty
+language: php
+
+php:
+  - 7.2
+  - nightly
+
+matrix:
+  allow_failures:
+    - php: nightly
+
+# This triggers builds to run on the new TravisCI infrastructure.
+# See: https://docs.travis-ci.com/user/reference/trusty#Container-based-with-sudo%3A-false
+sudo: false
+
+## Cache composer
+cache:
+  directories:
+    - $HOME/.composer/cache
+
+before_script:
+  - travis_retry composer update --no-interaction --prefer-dist
+
+script:
+  - vendor/bin/phpcs -p --standard=psr2 . include