text: Title: Add devices by IP address range
  Body: Hey, first off, thanks for antminer-monitor!  It's uncomplicated software that does its job well!
  
  Second, we were curious about adding devices by IP address range, for example:
  
  192.168.69.101-200: antminer S9
  192.168.70.1-250: antminer L3
  
  Or, is there a way to add these devices in a range using the command line that I just don't know about yet?  
  
  We might be able to add this functionality and submit a PR, if you can point us in the right direction.  Thanks!