Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=55314
Provide a container specific extension to the WsServerContainer to allow frameworks to more easily diaptch requests to WebSocket endpoints.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1514447 13f79535-47bb-0310-9956-ffa450edef68