Fixed Symfony versions used in matrix

Author: wouterj

.travis.yml

@@ -15,13 +15,18 @@ matrix:
     - php: hhvm
   include:
     - php: 5.6
-      env: SYMFONY_VERSION=2.4.*
-    - php: 5.6
-      env: SYMFONY_VERSION=2.5.*
+      env: SYMFONY_VERSION=2.3.*
     - php: 5.6
       env: SYMFONY_VERSION=2.6.*
     - php: 5.6
       env: SYMFONY_VERSION=2.7.*
+    - php: 5.6
+      env: SYMFONY_VERSION=3.0.*
+  allow_failures:
+    - php: 5.6
+      env: SYMFONY_VERSION=2.7.*
+    - php: 5.6
+      env: SYMFONY_VERSION=3.0.*
 
 before_script:
   - composer self-update