moved check_genesis_block function to p2pool.bitcoin.helper
added helper scripts
converted networks to new one file per network format using dev/convert_networks

If you're having trouble merging this commit, do this to apply what this commit
does to your networks:

    git reset HEAD . # reset index to your copy
    git checkout HEAD . # reset tree to your copy
    rm -fr p2pool/networks p2pool/bitcoin/networks # remove added files
    dev/convert_networks # convert networks to new format (what this commit does)
    git commit # finish the merge