Change key usage to a shallow copy

Author: iamanthropic

lib/sfPath.js

@@ -3,7 +3,7 @@ import {parse, stringify, normalize} from 'objectpath';
 
 let name = function(key, separator, formName, omitNumbers) {
   if(key) {
-    var fieldKey = key;
+    var fieldKey = key.slice();
     var fieldSeparator = separator || '-';
 
     if(omitNumbers){