Move CKEditor implementation in a contrib application

[sveetch]

Just so CKEditor is not a dependency anymore from lotus base and another contrib app could implement another editor like Summernote.

[sveetch]

I don't think actually that splitting features in another packages would be a good idea, this will make more maintenance work.

I choose to focus instead on #80 that should bring a way to implement your own editor but still include somes (at least CKEditor and another one).