Upgrade to CKEditor 4.1.1

This release brings with it the Advanced Content Filter, ACF. For
details I highly advise you read the following URL to work out if there
will be any potential issues:

- http://ckeditor.com/blog/Upgrading-to-CKEditor-4.1
(cherry picked from commit 2c35b26da150c24f2642b2410361040291533731)