SIDEBAR_IMAGE wont be shown unless AUTHOR_ABOUT is also set

That whole sidebar image was a mess-- still is, just a little less so. only the
image would look like spit. it would not have proper margins as there would be
no section heading. so we won't allow it (for now).

If AUTHOR_ABOUT is set then a section with the heading "About" gets rendered.
Within this section a possibly set SIDEBAR_IMAGE gets displayed. It will be
floating to the right. Proper margins will be set to have the text of
AUTHOR_ABOUT not touch the SIDEBAR_IMAGE.