update travis config

Author: lsmith77

.travis.yml

@@ -3,10 +3,11 @@ language: php
 php:
   - 5.3
   - 5.4
+  - 5.5
 
 before_script:
   - composer self-update
-  - composer install
+  - composer install --prefer-source
   - php app/console doctrine:database:create -e=test
   - php app/console doctrine:phpcr:init:dbal -e=test
   - php app/console doctrine:phpcr:workspace:create standard_test -e=test