Added OSHW Logo

Generated silkscreen for back silk based upon files available here:
http://oshwlogo.com/ Scaled image included.

Also moved some text to make room for the logo on the main panel.
Changed footprint soldermask clearance

The footprints used in the original design had too much soldermask
clearance (set to the default of .010 in). Changed to .002 to attempt to
get fab to lay soldermask between QFN pads. Did the same for the
"Mousebite" footprint, which is actually just 3 npth drills.