Update configuration.go to use all auth_servers
Update configuration.go to use all auth_servers

Only the last provided auth_server was being used.
yacloud-io/teleport,suedadam/teleport,bshelton229/teleport,aashley/teleport,tidalf/teleport,aashley/teleport,suedadam/teleport,tidalf/teleport,bshelton229/teleport,gravitational/teleport,gravitational/teleport,gravitational/teleport,gravitational/teleport,sokoow/teleport,bshelton229/teleport,bshelton229/teleport,ajvb/teleport,tidalf/teleport,sokoow/teleport,sokoow/teleport,gravitational/teleport,ajvb/teleport,aashley/teleport,ajvb/teleport,bshelton229/teleport,suedadam/teleport,sokoow/teleport,suedadam/teleport,ajvb/teleport,sokoow/teleport,yacloud-io/teleport,yacloud-io/teleport,tidalf/teleport,aashley/teleport,sokoow/teleport,suedadam/teleport,yacloud-io/teleport,yacloud-io/teleport,yacloud-io/teleport,gravitational/teleport,yacloud-io/teleport,ajvb/teleport,aashley/teleport,tidalf/teleport