#20 Create composite update site containing tomcatplugin and orbit update site

[MarkusK]

The default Tomcatplugin update site reachabele via http://tomcatplugin.sf.net/update should be a composite update site containing a reference to the tomcatplugin artifacts and the Eclipse Orbit Update Sites.

Therefore the "original" update site should be moved to another URL below http://tomcatplugin.sf.net