Styling changes for minimal setups
This change is necessary for minimal setups, e.g. for plain installs
during regression test, when no bootstrap packages are available.
- define yui as last-resort fallback for "toolkit"
- handle CSS class composition for YUI as well
(merge of class-specific and item specific CSS classes,
used for color management for publish status button)
- remove underline for publish-status in YUI mode
