Backport the new descriptor package (but not the parsers) to support some refactoring to use the new LocalResolver.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1547905 13f79535-47bb-0310-9956-ffa450edef68
Add the new descriptor package to the tomcat-util.jar

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1547906 13f79535-47bb-0310-9956-ffa450edef68
Add the unit test for the LocalResolver

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1547909 13f79535-47bb-0310-9956-ffa450edef68