Adding coinrpc to pybitcoin

This commit adds the (simplified) coinrpc library to pybitcoin with the following properties:

1) Rewrote the commit history, so all coinrpc commits are local to rpc/ folder in the history and won't conflict with any commits (e.g., README.md in the root directory)
2) Removed commits for files/folders that are no longer relevant for coinrpc (e.g., the old source of namecoinrpc that was used at one point instead of AuthProxy, the secure deployment of coinrpc that was compiled with cython, old backups and irrelevant/temp folders etc)
3) Ensured that commit history is in chronological order relative to current pybitcoin commit history