Switch to the faster Docker-based infrastructure

Author: stof

.travis.yml

@@ -16,12 +16,17 @@ matrix:
     - php: 5.6
       env: SYMFONY_VERSION='2.5.*'
 
+sudo: false
+
+cache:
+  directory:
+    - $HOME/.composer/cache
+
 before_install:
-  - composer self-update
   - sh -c 'if [ "$SYMFONY_VERSION" != "" ]; then composer require --no-update symfony/symfony=$SYMFONY_VERSION; fi;'
 
 install:
-  - composer install --prefer-source
+  - composer install
 
 script:
   - phpunit --coverage-text