Use dists in order to profit from Travis caching

Author: wouterj

.travis.yml

@@ -29,7 +29,7 @@ before_script:
   - composer self-update
   - sh -c 'if [ "$TRAVIS_PHP_VERSION" != "hhvm" ]; then echo "memory_limit = -1" >> ~/.phpenv/versions/$(phpenv version-name)/etc/conf.d/travis.ini; fi;' 
   - sh -c 'if [ "$SYMFONY_VERSION" != "no" ]; then composer require symfony/symfony:${SYMFONY_VERSION} --no-update; fi;'
-  - composer update --prefer-source
+  - composer update --prefer-dist
   - vendor/symfony-cmf/testing/bin/travis/phpcr_odm_doctrine_dbal.sh
 
 script: phpunit --coverage-text