remove php <5.5 from travis.yml

.travis.yml

@@ -5,7 +5,6 @@ language: php
 sudo: false
 
 php:
-  - 5.4
   - 5.5
   - 5.6
 
@@ -14,8 +13,6 @@ env:
 
 matrix:
   include:
-    - php: 5.3
-      env: DB=PGSQL CORE_RELEASE=3.1
     - php: 5.6
       env: DB=MYSQL CORE_RELEASE=3.2
     - php: 5.6