Enable codecov.io

Author: sebastianbergmann

.travis.yml

@@ -21,7 +21,10 @@ install:
   - travis_retry composer update --no-interaction --no-ansi --no-progress --no-suggest --optimize-autoloader --prefer-stable
 
 script:
-  - ./vendor/bin/phpunit
+  - ./vendor/bin/phpunit --coverage-clover=coverage.xml
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)
 
 notifications:
   email: false