use stable Symfony 2.8/3.0 releases

Author: xabbuh

.travis.yml

@@ -32,9 +32,9 @@ matrix:
     - php: 5.6
       env: SYMFONY_VERSION=2.7.* PHPUNIT_VERSION=~4.0
     - php: 5.6
-      env: SYMFONY_VERSION=2.8.*@dev PHPUNIT_VERSION=~4.0
+      env: SYMFONY_VERSION=2.8.* PHPUNIT_VERSION=~4.0
     - php: 5.6
-      env: SYMFONY_VERSION=3.0.*@dev PHPUNIT_VERSION=~4.0
+      env: SYMFONY_VERSION=3.0.* PHPUNIT_VERSION=~4.0
   allow_failures:
     - php: hhvm