shareSDK 第三方登录

http://wiki.sharesdk.cn/%E5%BF%AB%E9%80%9F%E9%9B%86%E6%88%90%E6%8C%87%E5%8D%97/#.E7.AC.AC.E4.BA.8C.E6.AD.A5.EF.BC.9A.E6.B7.BB.E5.8A.A0.E4.BE.9D.E8.B5.96.E6.A1.86.E6.9E.B6