api: add api-bind param -b 0.0.0.0:4068

possible values :

 5000 or :5000 to use port 5000 (local only)
  0.0.0.0:5000 to allow connections from the network
127.0.0.1:4068 to only allow local connections (default)

Use -b 0 to disable the API system.

Signed-off-by: Tanguy Pruvot <tanguy.pruvot@gmail.com>