update the lunach shortcut according to Ryu 3.8

Signed-off-by: Samuel Deng <mr.dengshuoling@gmail.com>
avoid push flows frequently.

Signed-off-by: Samuel Deng <mr.dengshuoling@gmail.com>
add host discovery module.

Signed-off-by: Samuel Deng <mr.dengshuoling@gmail.com>