initial commit of JSR 303 Bean Validation example project

git-svn-id: https://svn.apache.org/repos/asf/struts/sandbox/trunk@1536436 13f79535-47bb-0310-9956-ffa450edef68
Updated Struts 2 version to 2.3.15.3

git-svn-id: https://svn.apache.org/repos/asf/struts/sandbox/trunk@1536438 13f79535-47bb-0310-9956-ffa450edef68