Don't inject the interceptor in the list of selected interceptors for an operation if it's name is already in the list.
This solve a issue when we add an interceptor which extends an existing one (otherwise the operation would be executed twice)

git-svn-id: https://svn.apache.org/repos/asf/directory/apacheds/trunk@1477725 13f79535-47bb-0310-9956-ffa450edef68