New Wicket Portlet support: adding portlet support with a new WicketPortlet and support classes

The "real" thing: a new WicketPortlet, WicketPortletFilter and supporting classes to allow Wicket applications to run (unmodified) as portlets.
This brings in two new dependencies: portlet-api-1.0.jar and Apache Portals Bridges portals-bridges-common-1.0.2-beta1.jar

As the Portals Bridges common dependency isn't available from ibiblio but through the (default) bridges and Jetspeed-2 remote maven-1 and maven-2 repositories at www.bluesunrise.com, I also add that one as additional repository.

The portals-bridges-common-1.0.2-beta1.jar is needed for the PortletResourceURLFactory interface which allows creating pre-Portlet API 2.0 Portlet ResourceURLs by portals which implement it.
Jetspeed-2.1.1-beta1, which I "released" just a few days ago unofficially now provides an implementation of this interface, so that one can be used for testing the Wicket portlet-support.
This 2.1-1-beta1 release of Jetspeed-2 can temporarily be downloaded from http://people.apache.org/~ate until the formal release Jetspeed-2.1.1 which we've planned within one or two weeks from now.

Note also: this Wicket portlet support depends on request filtering during included requests, and hence will require a servlet API 2.4 supporting container!