For 3.1 we have the Site Logo extension that can do that, but it hasn't been made compatible with 3.2 yet and will only be when 3.2's stable release is released, according to the author. So, you can either wait till a version of the extension gets released that does deal with this, or make the necessary template edits to the overall_header.html file of the style you are using. Keep in mind that you'd have to re-do those template edits after every update, so waiting for the extension would be more sustainable.