JSONValidationInterceptor should generate valid JSON responses

The method protected String buildResponse(ValidationAware validationAware) in org.apache.struts2.interceptor.validation.JSONValidationInterceptor should generate valid JSON responses, right now it generates json-commenting responses but this could be worst http://trac.dojotoolkit.org/ticket/6380

In other side it breaks compatibillity with other frameworks like JQuery 1.4 (version 1.3 allow to parse non strict JSON) http://www.neeraj.name/2010/01/15/handling-json-parsing-natively-in-jquery-1-4-and-what-changed-from-jquery-1-3.html.

thank you