Major redesign of the configurator section:

- remove the service CvtSvc
- introduce a new module extjs containing a configurator class for each ExtJS component.
- introduce a new module converter containing helper function transforming web2py dal object into ExtJS configurator.
- deploy configurator in the rest of the code.
- define an xtype forl the App.Viewport class.
- Remove the widget class and transform the Spacer into a configurator.
- clean the navtree module. Helper function are replaced by configurator