code: public AVIMConversationsQuery whereWithinGeoBox(String key, AVGeoPoint southwest,
                                                    AVGeoPoint northeast) {
      conditions.whereWithinGeoBox(key, southwest, northeast);
      return this;
    }
docs: 增加一个基于地理位置的查询，当conversation的属性中有对应字段对应的地址位置在指定的矩形区域内时即可返回
  
  @param key       查询字段
  @param southwest 矩形区域的左下角坐标
  @param northeast 去兴趣鱼的右上角坐标
  @return