However, this is probably not exactly the test we'd ideally want here.  Image files are binary, but we probably _do_ want them listed in Quick Open results (because very soon you'll be able to preview them in Brackets).  We really want something more like "files we don't know what to do with," which is a subset of binary files.

For now, I think this is ok... but when this lands I'll need to make a note to revisit this on the feature card for image viewing.