[SPARK-6555] [SQL] Overrides equals() and hashCode() for MetastoreRelation

[liancheng]

Also removes temporary workarounds made in #5183 and #5251.

[SparkQA]

Test build #29472 has started for PR 5289 at commit cfafeeb.

[liancheng]

Actually the trouble maker is PlanTest.comparePlans, because now MetastoreRelation also compares output attributes. But right now I don't have a clean solution for this. Thus, I replace the original metastore relation with a temporary relation to pass the test here.

[marmbrus]

I think thats actually reasonable. Compare plans is mostly about checking plan structure.

[marmbrus]

I'd even be okay adding a special rule to compare plans that always replaces MetastoreRelations with LocalRelation

[SparkQA]

Test build #29474 has started for PR 5289 at commit d0095ac.

[SparkQA]

Test build #29472 has finished for PR 5289 at commit cfafeeb.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • case class AtLeastNNonNulls(n: Int, children: Seq[Expression]) extends Predicate
• This patch does not change any dependencies.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/29472/
Test PASSed.

[SparkQA]

Test build #29474 has finished for PR 5289 at commit d0095ac.

• This patch passes all tests.
• This patch merges cleanly.
• This patch adds no public classes.
• This patch does not change any dependencies.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/SparkPullRequestBuilder/29474/
Test PASSed.

[liancheng]

All changes above this line are about reverting workaround introduced in #5183.

[marmbrus]

Thanks! Merged to master and 1.3