[SPARK-8837][SPARK-7114][SQL] support using keyword in column name

[cloud-fan]

No description provided.

[cloud-fan]

cc @rxin @marmbrus

[AmplabJenkins]

Merged build triggered.

[AmplabJenkins]

Merged build started.

[SparkQA]

Test build #36570 has started for PR 7237 at commit e7b49bb.

[SparkQA]

Test build #36570 has finished for PR 7237 at commit e7b49bb.

• This patch fails Scala style tests.
• This patch merges cleanly.
• This patch adds the following public classes (experimental):
  • case class Decode(bin: Expression, charset: Expression)

[AmplabJenkins]

Merged build finished. Test FAILed.

[cloud-fan]

retest this please.

[AmplabJenkins]

Merged build triggered.

[AmplabJenkins]

Merged build started.

[SparkQA]

Test build #36574 has started for PR 7237 at commit e7b49bb.

[SparkQA]

Test build #36574 has finished for PR 7237 at commit e7b49bb.

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

[AmplabJenkins]

Merged build finished. Test PASSed.

[rxin]

cc @marmbrus

[marmbrus]

Thanks! Merging to master.

[marmbrus]

Actually apache is down... will merge when its back up...

[rxin]

git is back. I've merged this.