Adding a property 'jdk.xml.resolveExternalEntities' that can be used to globally disable the resolution of external general/parameters entities and the external DTD.

git-svn-id: https://svn.apache.org/repos/asf/xerces/java/branches/xml-schema-1.1-dev@1564074 13f79535-47bb-0310-9956-ffa450edef68