Fixed travis config

Author: Graham Campbell

.travis.yml

@@ -1,7 +1,7 @@
 language: php
 
 php:
-  - 5.4
+  - 5.5.9
   - 5.5
   - 5.6
   - 7.0
@@ -13,9 +13,9 @@ env:
 
 matrix:
   include:
-    - php: 5.4
+    - php: 5.5.9
       env: setup=lowest
-    - php: 5.4
+    - php: 5.5.9
       env: setup=stable
 
 sudo: false