Minor update 2
Minor update 2

* 修复少量bug
* 默认打开自动模式
* 用sscanf进行串口数据判断，更省内存而且可以兼容老sdk
* rtc微调改用RTClib的TimeSpan，省去大坨计算和判断

使用Arduino IDE 1.6.13编译
Sketch uses 17,342 bytes (53%) of program storage space. Maximum is
32,256 bytes.
Global variables use 565 bytes (27%) of dynamic memory, leaving 1,483
bytes for local variables. Maximum is 2,048 bytes.

zhangjingye03/smart_666,zhangjingye03/smart_666,zhangjingye03/smart_666