XX-11168: Update web.xml to use servlet 3.0 capabilities including websocket support in sipXconfig

-update web.xml to servlet 3.0 spec
-add spring 4 web socket api dependencies
-add STOMP (with keep-alive capabilities - version 1.1) and SockJs java script APIs
-add websocket capabilities to the new Jetty 9.1.5 (include Jetty 9.1.5 websocket jars in sipxconfig classpath)
-create ws path below CXF /api (api/ws) and map it with spring servlet to route ws packets - same security rules as for CXF /api path
-the websocket router (spring servlet) inherits sipXconfig root context, and has a dedicated child context (empty now: ws-servlet.xml)
and can benefit of all sipxconfig context beans and event listener mechanisms (DaoListener for example)
-websocket app to receive change (save/update) phone notifications(using stomp/sockJs/spring4)
-reuse CXF REST beans and perform automatic marshaling between JAVA pojo and JSON websocket packet(using jackson API & STOMP 1.1)