added a readme
Add PSU schematic

Eagle files, Gerbers and more for the PSU have been added. Refer to included
dcumentation for more details.
Fixed unrouted airwire on VBUS net

Somehow I ripped up a track after exporting gerbers, and committed the wrong
psu.brd. This commit fixes that. The gerbers looked right, and I think they
were, but I regenerated them all to be sure - only the top copper layer was
minorly affected by the fix. Eagle layouts are XML-based, so you can see the
fix in the diff.

Also switched from pdfs to pngs for all exported output. Makes it easier to
view in-browser. One image for the schematic (was too small in last commit),
one for eagle board layout, and one for gerbers from gerbv.
Minor readme corrections

GitHub support staff kindly removed this repo from the upstream fork network on my request, so the readme needed some tweaks. I also updated the readme to reflect the preliminary schematics that were added earlier.
Add preliminary case design

The files in this commit represent an intermediate design of the acrylic case
for the project. There are probably a few more changes in store for this part,
but it's good enough to put online right now.