[SPARK-20385][WEB-UI] Submitted Time' field, the date format needs to be...

[SPARK-20385][WEB-UI] Submitted Time' field, the date format needs to be formatted, in running Drivers table or Completed Drivers table in master web ui.

## What changes were proposed in this pull request?
Submitted Time' field, the date format **needs to be formatted**, in running Drivers table or Completed Drivers table in master web ui.
Before fix this problem  e.g.

Completed Drivers
Submission ID	             **Submitted Time**  	             Worker	                            State	   Cores	   Memory	       Main Class
driver-20170419145755-0005	 **Wed Apr 19 14:57:55 CST 2017**	 worker-20170419145250-zdh120-40412	FAILED	   1	       1024.0 MB	   cn.zte.HdfsTest

please see the  attachment:https://issues.apache.org/jira/secure/attachment/12863977/before_fix.png

After fix this problem e.g.

Completed Drivers
Submission ID	             **Submitted Time**  	             Worker	                            State	   Cores	   Memory	       Main Class
driver-20170419145755-0006	 **2017/04/19 16:01:25**	 worker-20170419145250-zdh120-40412	         FAILED	   1	       1024.0 MB	   cn.zte.HdfsTest

please see the  attachment:https://issues.apache.org/jira/secure/attachment/12863976/after_fix.png

'Submitted Time' field, the date format **has been formatted**, in running Applications table or Completed Applicationstable in master web ui, **it is correct.**
e.g.
Running Applications
Application ID	                Name	                Cores	Memory per Executor	   **Submitted Time**	      User	   State	        Duration
app-20170419160910-0000 (kill)	SparkSQL::10.43.183.120	1	    5.0 GB	               **2017/04/19 16:09:10**	  root	   RUNNING	    53 s

**Format after the time easier to observe, and consistent with the applications table,so I think it's worth fixing.**

## How was this patch tested?

(Please explain how this patch was tested. E.g. unit tests, integration tests, manual tests)
(If this patch involves UI changes, please attach a screenshot; otherwise, remove this)

Please review http://spark.apache.org/contributing.html before opening a pull request.

Author: 郭小龙 10207633 <guo.xiaolong1@zte.com.cn>
Author: guoxiaolong <guo.xiaolong1@zte.com.cn>
Author: guoxiaolongzte <guo.xiaolong1@zte.com.cn>

Closes #17682 from guoxiaolongzte/SPARK-20385.