[web server] vregistry may now be passed as named argument in CubicWebRootResource constructor This will be needed to start an http server for testing purpose. Also, server run command has now a debug name argument to set debug mode explicitly

# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
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%(long-license)s
"""%(distname)s specific hooks and operations"""