ISIS-323: mark RestfulObjectsSpecEventSerializer as @Hidden...

... so does not appear in UI.
ISIS-335: abbreviate title in collections.
ISIS-336: fixing CSS for disabled menu items in Wicket viewer.
ISIS-336: reduce size of font in breadcrumbs in Wicket viewer.
ISIS-337: reduce font size of breadcrumbs in Wicket viewer

* this is a dummy commit;
* previous commit should have referenced ISIS-337, not ISIS-336