Apply the cash drawer fix detailed in Issue 10 on the Google Code repo.

https://code.google.com/p/python-escpos/issues/detail?id=10
Ensure QR codes have a border large enough for successful scan

(The QR code spec requires a border at least 4*box_size thick but we can't
 just set border=16 because that results in a QR code more than 255px tall
 and I'm not yet ready to use fullimage() as a backend for it)