Merge pull request #87 from spaze/spaze/is_numeric_double

Check if the value is numeric string first before is_double()

src/Common/Internal/Utilities.php

@@ -848,7 +848,7 @@ class Utilities
      */
     public static function isDouble($value)
     {
-        return is_double($value + 0);
+        return is_numeric($value) && is_double($value + 0);
     }
 
     /**