Add cleanup-zk script
Merge pull request #61 from changbl/working

Add cleanup-zk script
Fix DHCP and change bin scripts

(1) Fix DHCP bug of unpacking mac_to_position tuples

(2) Change bin scrpits so that no longer need to specify "PYTHONPATH"
and "--config-file"
Merge pull request #62 from changbl/working

Fix DHCP and change bin scripts