emqttd#787: Stop plugins before the broker stopped, clean routes when a node down

emqttd#790: Unable to start emqttd service if username/password contains special characters

emq-auth-clientid#4: Improve the configuration of emq_auth_clientid.conf to resolve emqttd#790

emq-auth-username#4: Improve the configuration of emq_auth_username.conf to resolve emqttd#790