v5.7.1

Added missing badSocketAuthToken event on the server. See http://socketcluster.io/#!/docs/api-scserver
Added missing badAuthToken event on the server-side socket. See http://socketcluster.io/#!/docs/api-scsocket-server

Note that the documentation for these events existed on the website for a long time but these events were actually missing in new versions of SC until now. Note that the docs on the website have been updated to reflect the latest implementation.