Fix missing valuesOptions in fromJSON parser function

I've found out that the "valuesOptions" option in the Enum class is missing when parsed from the JSON.

This PR should fix the issue: protobufjs#1961

src/enum.js

@@ -87,7 +87,7 @@ function Enum(name, values, options, comment, comments, valuesOptions) {
  * @throws {TypeError} If arguments are invalid
  */
 Enum.fromJSON = function fromJSON(name, json) {
-    var enm = new Enum(name, json.values, json.options, json.comment, json.comments);
+    var enm = new Enum(name, json.values, json.options, json.comment, json.comments, json.valuesOptions);
     enm.reserved = json.reserved;
     return enm;
 };