设置 header,
AFHTTPClient *client = [[AFHTTPClient alloc]initWithBaseURL:[NSURL URLWithString:SERVER_TENCENT]];
[client registerHTTPOperationClass:[AFJSONRequestOperationclass]];
[client setDefaultHeader:@"Accept"value:@"application/json"];
[client postPath:PATH_TENCENT_USERINFO parameters:parmas success:^(AFHTTPRequestOperation *operation, id responseObject) {