First draft of high resolution 2-sided wallet

This removes much of the (albeit excellent) functionality from
bitaddress.org to create a streamined step-by-step paper wallet printer
for novices. Includes a tool to help users "calibrate" their printer
for more consistent output between different browsers. Renamed main
.html file to avoid confusion with bitaddress.org. Moved images into
their own directory since they will be quite large and might not do
well encoded into the JS anymore.