Added a new demo, that we'll also add to ckeditor.com. Note: It was created by copy&pasting the Classic demo, that's why it contains some boilerplate files that I didn't actually need. But it's consistent with its origin.
Fixed some random issues I found:
Use of CKFinder together with CKBox. (BTW: there's still CKBox+Base64 loaded together, but this actually makes sense because Base64 becomes a backup if someone didn't set CKBox's token URL).
Messed up gitignore files.
Fixed a bit the styling for document editor. But it requires more work to align it to ckeditor.com counterpart.