- CGI script and index.html are moved from gluon-web to
gluon-config-mode-core, the script is renamed to 'config'
- gluon-web and gluon-web-model base views and i18n files are symlinked
into the new path
- gluon-web-theme is renamed to gluon-config-mode-theme and installs
directly into the new path
- all gluon-web-* models, controllers and views are moved into the new
path
If a value is unset or optional, an empty choice is added to the selection.
This empty choice will be marked as invalid if the value is not optional.
This is properly supported for the 'select' widget only for now, and not
for 'radio'.
