Corrected PHP version.

cxj · cxj · commit 5b9cfebc6e2b · 2015-11-13T14:59:12.000-06:00
PHP 5.4 does not support initializations using expressions containing constants.
diff --git a/composer.json b/composer.json
@@ -21,7 +21,7 @@
     },
 
     "require": {
-        "php": ">=5.4",
+        "php": ">=5.5",
         "psr/log": "^1.0",
         "icecave/isolator": "~2|~3"
     },
