Issue title: 警告问题：isMounted(...) is deprecated in plain JavaScript React classes.
 Issue body: 
使用了表格组件后，控制台连续警告：isMounted(...) is deprecated in plain JavaScript React classes.
![image](https://user-images.githubusercontent.com/9399517/32100824-f578df2a-bb47-11e7-93f9-ce736c2f5b81.png)


![image](https://user-images.githubusercontent.com/9399517/32100695-591f3e30-bb47-11e7-90e2-e5755e4ade2b.png)




 Comments: 
 Comment 0: 不影响使用的，暂时可以忽略，会在下一版中修复
 Comment 1: 请升级到griffindenise@example.org`试试看, 暂时先关闭这个issue, 有问题随时可以重新打开.
{'source': 'GithubIssues', 'repo_name_with_owner': 'eleme/element-react', 'issue_id': 269066542, 'repo_stars': 1688.0}