Added LuciDeviceScanner to scan OpenWrt Luci-RPC enabled router's state.

[fingon]

Just to play with it, implemented tracker for devices on Luci-based router.

For the time being, just getting MAC addresses from ARP table, and name->MAC mappings from dhcp configuration. As I'm planning to write my own logic backend for which this is sufficient, it's enough for me, but it may not work that well with the vanilla logic (due to ARP entries having short lifetime and quiet devices not sending any).

I'm not sure there's any low-power approach how to ensure that devices are present in the first place though.. (DHCP leases for example aren't that good way to track presence of hosts either.)

[balloob]

Cool :-)

Before I can accept it I would like to see some style / code clean up changes:

• all code has to go through the tools pep8 and pylint without generating warning/error. Among others no lines above 80 characters.
• There are still comments and catching of exceptions related to the Tomato scanner
• Use list comprehension instead of map to keep the code more readable:
  list(map(lambda x:x['HW address'], r.json()['result'])) can be rewritten more clear as [item['HW address'] for item in r.jsoin()['result']]