simplifying the bitrpc script

I'm pythonwiz from reddit. My bitcoin address is 16XRJjqUuaHMT1RkDbQ7ti7gihF6v3SKu5. I added a list of supported rpc calls to the README, and I reduced the size of the bitrpc script by about a factor of 5 (as you can see in the diffs below.) I can add comments if you'd like.