Upgrade CKEditor to 4.7

CKEditor 4.7 is out. It contains several nice features, like "copy formatting" and improved paste-from-word. It also has a new default skin, which is 'flat', so it matches a lot better with the look-and-feel of Hippo CMS. That would allow us to remove some CKEditor styling customizations.

We should upgrade to it to stay up-to-date and to roll out these new features to customers. My suggestion is to include CKEditor 4.7 in 12.0.