title: Add global EventListener in pax-web
body: <p><code>org.ops4j.pax.web.service.WebContainer</code> has method <code>registerEventListener(java.util.EventListener, org.osgi.service.http.HttpContext)</code> that allows, for example, register session listener.</p>
  
  <p>The problem is, that it registers listener only for given HttpContext, which is, generally, the context of the calling bundle. Therefore I'm unable to register session listener for rest channels that were registered by JAXBPublisher, because I'm unable to get its HttpContext.</p>
  
  <p>Is it possible to register global <code>EventListener</code>? </p>