Allow user styles to effect divs that are not editable

I'm not clear why, but previously the StyleEditor code assumed and required that user modified style rules began with ".bloom-editable". This made it impossible to have make a page where, if the user modified the style of some editable box, other elements on the page would change as well, in order to keep the page consistent. The particular page for which this came up was the credits page, where a big chunk of the page is not .bloom-editable's.
I think I was just trying to distinguish styles that applied to editable blocks, which I assumed would be the only ones the user could sensibly edit, from all the other ones that are used for page layout and the editing process. If removing the requirement is not causing obvious problems, it's probably fine. The one caution that occurs to me: without this restriction, what happens if a user happens to create (and thus redefine) a style used for something in the UI? But that can't happen as long as we don't use style names ending in -style for anything the user shouldn't modify.