added clover coverage

Author: Nick Goris

.travis.yml

@@ -9,7 +9,8 @@ before_script:
   - composer self-update
   - composer install --prefer-source --no-interaction --dev
 
-script: composer test
+script:
+    - vendor/bin/phpunit --coverage-clover=coverage.xml
 
 after_success:
   - bash <(curl -s https://codecov.io/bash)