[GraphX] Improve LiveJournalPageRank example

[jackylk]

1. Removed unnecessary import
2. Modified usage print since user must specify the --numEPart parameter as it is required in Analytics.main

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Test build #28299 has started for PR 4917 at commit 5caae76.

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[srowen]

Are you sure you can remove this one? it imports implicits right?
This change loses the description of the parameter too.
This is on the border of non-trivial, but if it's merely fixing the usage note, seems OK.

[jackylk]

Yes, I think it is OK.
The description of the parameter will be output by the Analytics.Main, looks like:

JackydeMacBook-Pro:spark jackylee$ bin/run-example graphx.LiveJournalPageRank ../data/Wiki-Vote.txt
Set the number of edge partitions using --numEPart.
Using Spark's default log4j profile: org/apache/spark/log4j-defaults.properties
JackydeMacBook-Pro:spark jackylee$ 

[srowen]

Yes, but, why remove the description, which already existed in the help message in this file?

[jackylk]

Yes, you are right. I modified back, just remove the default value description

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Test build #28299 has finished for PR 4917 at commit 5caae76.

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Test build #28319 has started for PR 4917 at commit 87be83b.

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Test build #28319 has finished for PR 4917 at commit 87be83b.

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[srowen]

Eh, but now you have put the option in twice! why not just move it up and remove the square braces to mark it non-optional? keep everything else the same.

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Test build #28369 has started for PR 4917 at commit b6235e6.

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Test build #28369 has finished for PR 4917 at commit b6235e6.

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Test build #28370 has started for PR 4917 at commit c0df8f2.

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Test build #28370 has finished for PR 4917 at commit c0df8f2.

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[srowen]

OK, but now there is this unrelated change in your PR.

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Test build #28373 has started for PR 4917 at commit 6c07682.

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Test build #28373 has finished for PR 4917 at commit 6c07682.

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