Use the value of the `name` site.conf field as label (it was
accidentally unused before).
Our site.conf currently doesn't define a specific order for the branch
entries. To avoid changing branch orders, sort entries by this label.
Fixes: #1961
- 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
