update ckeditor to 4.0.1

note that now ckeditor has a builder in http://http://ckeditor.com/builder
current config is in devel/third-party/ckeditor/build-config.js
restore our customization for ckeditor
explicitly set toolbarCanCollapse to make toolbar collapsible

seems new version of ckeditor doesn't enable this by default any more
Merge branch '4.2/update-ckeditor'