cache on travis

Author: Nyholm

.travis.yml

@@ -18,7 +18,7 @@ sudo: false
 before_script:
     - composer self-update
     - composer require symfony/symfony:${SYMFONY_VERSION} --no-update
-    - composer install --dev --prefer-source --no-interaction
+    - composer install --dev --prefer-dist --no-interaction
 
 script:
     - php vendor/bin/phpunit