Attempts add or remove a IP/Subnet from the banned list.
Arguments: 1. "ip(/netmask)" (string, required) The IP/Subnet (see getpeerinfo for nodes ip) with a optional netmask (default is /32 = single ip) 2. "command" (string, required) 'add' to add a IP/Subnet to the list, 'remove' to remove a IP/Subnet from the list 3. "bantime" (numeric, optional) time in seconds how long (or until when if [absolute] is set) the ip is banned (0 or empty means using the default time of 24h which can also be overwritten by the -bantime startup argument) 4. "absolute" (boolean, optional) If set, the bantime must be a absolute timestamp in seconds since epoch (Jan 1 1970 GMT)