rais min-php version to 5.4.x. Refs dompdf#1597

Author: staabm

composer.json

@@ -25,7 +25,7 @@
         "classmap" : ["lib/"]
     },
     "require": {
-        "php": ">=5.3.0",
+        "php": ">=5.4.0",
         "ext-gd": "*",
         "ext-dom": "*",
         "ext-mbstring": "*",