Got it building for Rust v0.10

One note - I added a `sed` line to the Rakefile to get it to pass LLVM compilation. It seems like this makes it work with LLVM v3.3 but isn't necessary for v3.4. 

FYI I'm doing a talk on Thursday, "Programming an Arduino in Rust" at GlueCon in Broomfield, Colorado. I'm planning on using this code (with a more elaborate circuit) as a demo and to walk through some of the steps. Let me know if there's anything that should be mentioned or avoided.