[Spark-5717] [MLlib] add stop and reorganize import

[hhbyyh]

Trivial. add sc stop and reorganize import
https://issues.apache.org/jira/browse/SPARK-5717

[SparkQA]

Test build #27198 has started for PR 4503 at commit 2e85cc1.

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[SparkQA]

Test build #27198 has finished for PR 4503 at commit 2e85cc1.

• This patch fails Spark unit tests.
• This patch merges cleanly.
• This patch adds no public classes.

[AmplabJenkins]

Test FAILed.
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[hhbyyh]

The ut failure seems irrelevant. Not sure how to trigger the retest properly.

[srowen]

The Spark imports were correctly ordered already. I think the scopt import could go after the log4j import, if we're matching style of other imports.

[hhbyyh]

OK.

[srowen]

Yes it's a small thing but the examples should call stop(). I can merge if you'll move the imports accordingly.

[SparkQA]

Test build #27208 has started for PR 4503 at commit 7837a2c.

• This patch merges cleanly.

[srowen]

jenkins, retest this please

[SparkQA]

Test build #27209 has started for PR 4503 at commit 7837a2c.

• This patch merges cleanly.

[SparkQA]

Test build #27208 has finished for PR 4503 at commit 7837a2c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

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Test PASSed.
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[SparkQA]

Test build #27209 has finished for PR 4503 at commit 7837a2c.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.

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Test PASSed.
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