updated travis setup

Author: lsmith77

.travis.yml

@@ -3,18 +3,22 @@ language: php
 php:
     - 5.3
     - 5.4
+    - 5.5
 
 env:
   - SYMFONY_VERSION=2.2.*
   - SYMFONY_VERSION=2.3.*
   - SYMFONY_VERSION=dev-master
 
 before_script:
-  - composer require symfony/routing:${SYMFONY_VERSION} --no-update
-  - composer install --dev
+  - composer require symfony/routing:${SYMFONY_VERSION} --prefer-source
 
 script: phpunit --coverage-text
 
 notifications:
   irc: "irc.freenode.org#symfony-cmf"
   email: "[email protected]"
+
+matrix:
+  allow_failures:
+    - env: SYMFONY_VERSION=dev-master