Remove hardcoded references to pages and SiteTree
Remove assumption that records are versioned
Remove or validate assumptions about methods on the model class
Improve general architecture of CMSMain
* Various refactoring to support viewing list view in context menu and suppressed tree node
* Bugfixes per Maxime review
* Fix URL param collision
* Fix show in list on detail view
* Remove AJAX for show in list. Use hard refresh to keep URL state