Remove non-LTS versions from Travis

Author: matthiasnoback

.travis.yml

@@ -1,17 +1,12 @@
+sudo: false
+
 language: php
 
 matrix:
   include:
     - php: 5.4
-    - php: 5.5
-    - php: 5.6
-      env: SYMFONY_VERSION=2.5.*
-    - php: 5.6
-      env: SYMFONY_VERSION=2.6.*
     - php: 5.6
       env: SYMFONY_VERSION=2.7.*
-    - php: 5.6
-      env: SYMFONY_VERSION=2.8.*
     - php: 5.6
       env: SYMFONY_VERSION=3.0.*
     - php: 7.0