Remove tests for < PHP 5.6

Author: Crizz0

.travis.yml

@@ -4,18 +4,12 @@ dist: precise
 
 matrix:
   include:
-    - php: 5.4
-      env: DB=mysqli
-    - php: 5.4
-      env: DB=mysql
-    - php: 5.4
+    - php: 5.6
       env: DB=mariadb
-    - php: 5.4
+    - php: 5.6
       env: DB=postgres
-    - php: 5.4
+    - php: 5.6
       env: DB=sqlite3
-    - php: 5.5
-      env: DB=mysqli
     - php: 5.6
       env: DB=mysqli
     - php: 7