Add travis config file back in

Author: mikebronner

.travis.yml

@@ -0,0 +1,16 @@
+language: php
+
+php:
+    - 5.4
+    - 5.5
+    - 5.6
+    - 7.0
+    - hhvm
+
+before_script:
+    - travis_retry composer self-update
+    - travis_retry composer install --no-interaction --prefer-source --dev
+
+script: phpunit --coverage-text --coverage-clover ./build/logs/clover.xml
+
+after_script: php vendor/bin/coveralls