[SPARK-6228] [network] Move SASL classes from network/shuffle to network...

[vanzin]

.../common.

No code changes. Left the shuffle-related files in the shuffle module.

[SparkQA]

Test build #28399 has started for PR 4953 at commit 664ef30.

• This patch merges cleanly.

[SparkQA]

Test build #28399 has finished for PR 4953 at commit 664ef30.

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

[AmplabJenkins]

Test PASSed.
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Test PASSed.

[srowen]

It's strictly a code move, from child to parent module. Although I've never been that familiar with this code, I understand the motivation, to use it from the other child module, which seems sound. I'll let it stay open for a day or two in case there are other thoughts. If not I think this can merge.

[aarondav]

LGTM too.