[FIX] fixes a typo 'widet_config' => 'widget_config' (it previously crashed...

[FIX] fixes a typo 'widet_config' => 'widget_config' (it previously crashed the graph view) (addon web_graph)

bzr revid: ged@openerp.com-20140117085842-vxaxes0yv3dr7t24