Add travis-ci configuration

Author: Gianluca Arbezzano

.travis.yml

@@ -0,0 +1,21 @@
+language: php
+
+php:
+    - 5.3
+    - 5.4
+    - 5.5
+    - 5.6
+    - 7
+    - hhvm
+
+before_script:
+    - composer self-update
+    - composer install
+
+script:
+    - vendor/bin/phpunit
+
+branches:
+  only:
+    - master
+    - develop