[SPARK-14423][YARN] Avoid same name files added to distributed cache again

## What changes were proposed in this pull request?

In the current implementation of assembly-free spark deployment, jars under `assembly/target/scala-xxx/jars` will be uploaded to distributed cache by default, there's a chance these jars' name will be conflicted with name of jars specified in `--jars`, this will introduce exception when starting application:

```
client token: N/A
	 diagnostics: Application application_1459907402325_0004 failed 2 times due to AM Container for appattempt_1459907402325_0004_000002 exited with  exitCode: -1000
For more detailed output, check application tracking page:http://hw12100.local:8088/proxy/application_1459907402325_0004/Then, click on links to logs of each attempt.
Diagnostics: Resource hdfs://localhost:8020/user/sshao/.sparkStaging/application_1459907402325_0004/avro-mapred-1.7.7-hadoop2.jar changed on src filesystem (expected 1459909780508, was 1459909782590
java.io.IOException: Resource hdfs://localhost:8020/user/sshao/.sparkStaging/application_1459907402325_0004/avro-mapred-1.7.7-hadoop2.jar changed on src filesystem (expected 1459909780508, was 1459909782590
	at org.apache.hadoop.yarn.util.FSDownload.copy(FSDownload.java:253)
	at org.apache.hadoop.yarn.util.FSDownload.access$000(FSDownload.java:61)
	at org.apache.hadoop.yarn.util.FSDownload$2.run(FSDownload.java:359)
	at org.apache.hadoop.yarn.util.FSDownload$2.run(FSDownload.java:357)
	at java.security.AccessController.doPrivileged(Native Method)
	at javax.security.auth.Subject.doAs(Subject.java:422)
	at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1628)
	at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:356)
	at org.apache.hadoop.yarn.util.FSDownload.call(FSDownload.java:60)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
	at java.util.concurrent.FutureTask.run(FutureTask.java:266)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)
```

So here by checking the name of file to avoid same name files uploaded again.

## How was this patch tested?

Unit test and manual integrated test is done locally.

Author: jerryshao <sshao@hortonworks.com>

Closes #12203 from jerryshao/SPARK-14423.