We're going to change CKEditor to an inline editor, and the "ckeditor"
gem doesn't provide an option to do so.
Since using `cktext_area` would automatically generate a "classic"
iframe CKEditor, we need to use `text_area` and load the editor using
JavaScript. Personally I prefer this option anyway.
Note in the jQuery selector we need to use `textarea.html-area`; using
just `.html-area` would fail if there's an error message associated to
the textarea, since Rails will add the `.html-area` class to the error
message.
