Show purchase weight on admin details page.

Shows purchase weight if non-zero on admin details page.  This makes all information required to
create a shipping label available in one place.

Fixed section titles to not have duplicates.

Changed header elements to consistantly use blockquotes rather than paragraphs.

Added style information that tightens up the page a little bit show more information.  It might have changed a little bit with
the revised WordPress admin UI.
Merge remote-tracking branch 'origin/admin-show-purchase-weight'