Changes to style the showcard page

- Added the logo for balance.
- Gave the barcode some padding and margins
- Wrapped everything similarly to the "home" page, but the barcode
  function has some oddities so it's not quite as "nifty"
  (particularly the variable length aspect of the barcode.)
- Ready to be tested on as many devices as possible for bugs (as
  should everything be at this point, other than the location
  selector).

Signed-off-by: William Rockwood <wrockwood@tadl.org>