Update travis config

.travis.yml

@@ -1,11 +1,12 @@
 language: php
 
 php:
+  - 5.3.3
   - 5.3
   - 5.4
+  - 5.5
 
 before_script:
-  - curl -s http://getcomposer.org/installer | php
-  - php composer.phar install --dev
+  - composer install --dev --prefer-source
 
 script: phpunit