[Nostromo] Add Travis config

.travis.yml

@@ -0,0 +1,12 @@
+language: php
+php:
+  - '5.5'
+  - '5.6'
+  - '7.0'
+  - '7.1'
+
+install:
+  - composer install --prefer-source
+
+script:
+  - phpunit