Add Configfile for pconfigure

pconfigure is a build system that I wrote.  I've been maintaining a
Chisel fork for a while that builds with pconfigure.  Over break I'm
trying to get some of my forks merged, so I figured this would be a
good way to start.

This shouldn't cause anyone trouble because the sbt stuff is
completely untouched -- in other words if you don't want to use
pconfigure (ie, everyone else :)) then just ignore it!