Ckeditor update updates messages

Supercedes #2939 ; This PR features correct commit messages.

On top of the original contribution, I added:

The built files. There's no reason to automate this now.
Documentation on how to build.
This should make CKE work "immediately" - i.e. you check out this branch and CKE works when you hit the new/edit/translate pages.

If this "approved", we DO NOT MERGE YET but push this branch to mozilla/master and put it on staging.