Add structure to receive WebSocket backport from trunk

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1514522 13f79535-47bb-0310-9956-ffa450edef68
Copy JSR-356 WebSocket API and implementation from trunk into new Tomcat 7 module

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1514525 13f79535-47bb-0310-9956-ffa450edef68