refresh auth token regularly

Set up an interval on player login that periodically sends a new
authentication token to the player's client.
more robust request error handling

* immediately disconnect from client on authentication errors (to
  prevent client from sending subsequent messages which cannot be
  processed, spamming ERRORs)
* disconnect clients sending non-login requests before authentication
* bugfix: message ID property in AMF messages is called 'msg_id', not
  'id' (client still does not seem to do anything with error
  responses, though)
Merge pull request #38 from yelworc/token-refresh

automatic auth token refresh