Edit and add old WYM class back in, fix expression to behave as
intended.

Since jquery 1.2, the [@attr] has been deprecated, and removed since 1.3
(@cite: http://api.jquery.com/category/selectors/attribute-selectors/)

CMS appears to be running 1.4 -- so this doesn't work.

Absence causes no obvious bug, but the exclusive selection in the
texteditor not to work as demonstrated/written in settings file.  More
confusingly, without the "important" example, it's not at all obvious
why the selector is excluding hidden-note (There's no style to exclude)

Note:  You still can't actually see this working without including
appropriate classes in your template pages, and I'm not 100% confident
that the WYM_STYLESHEET is working.
Merge branch 'develop' of github.com:at3560k/django-cms into develop