Add new features, registered MAC address authentication

* The registered MACs are binding to the user, therefore, the devices
  with those MAC addresses is automatically logging in with binding
  username.  The accounting is recorded as normal as the user login
  with web login.

  FreeRADIUS with special MAC authen configuration is required.

Signed-off-by: Neutron Soutmun <neo.neutron@gmail.com>