The website_theme_install module now adds a link in the theme customize
modal to propose to install a theme when none is installed.
Also correct the name of the theme_default customize modal template.
* Remove recursive assets inclusions (i.e. assets_editor was including
assets_common, summernote, ...)
* Better construct the assets (link, then script + type attribute)
* Better include the assets (split js / css, always use t-call-assets)
* Simplifies the number of assets
* Move bootstrap js to assets common
* assets_frontend is now created by web module to allow using it on the
connexion page but also in the web_editor, where colors have to be
bootstrap/theme ones. Note: if a module depends on website, then keep
using the inherit_id="WEBSITE.assets_frontend"
Yannick Tivisse