Merged webvirtmgr-novnc-new into a smarter webvirtmgr-novnc

Further changes to the proxy starter to avoid the need of choose the right script to launch.

With this commit the user just needs to launch the webvirtmgr-novnc script and it will take care of choosing the right way to setup the server (either with novnc, websockify < 0.6.0 or websockify == 0.6.0)