Call emit_stats when force GC (emqttd#1071)

    Update the default value of ‘mqtt.mqueue.max_length’ to 1000 (emqttd#1074)

    Update default password field (emq-auth-mongo#67)

    Upgrade the mongodb library to v3.0.3

    认证支持HGET查询

    支持mongodb集群、Replica Set