add default config.json

[0x3639]

{
    "Producer": {
        "Index": 0,
        "KeyFilePath": "producer",
        "Password": "REDUCE",
        "Address": "REDUCE"
    },
    "Net": {
        "MinPeers": 8,
        "MinConnectedPeers": 8,
        "MaxPeers": 16,
        "MaxPendingPeers": 32
    }
}