添加针对所有人的群发属性

参考：http://mp.weixin.qq.com/wiki/15/5380a4e6f02f2ffdc7981a8ed7a40753.html
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D.E5.8A.A1.E5.8F.B7.E8.AE.A4.E8.AF.81.E5.90.8E.E5.9D.87.E5.8F.AF.E7.94.A
8.E3.80.91