## What changes were proposed in this pull request?
This is for users who can't upgrade and need to continue to use HiveContext.
## How was this patch tested?
Added some basic tests for sanity check.
This is based on #12672 and closes#12672.
Author: Andrew Or <andrew@databricks.com>
Author: Reynold Xin <rxin@databricks.com>
Closes#12682 from rxin/add-back-hive-context.
## What changes were proposed in this pull request?
This PR creates a compatibility module in sql (called `hive-1-x-compatibility`), which will host HiveContext in Spark 2.0 (moving HiveContext to here will be done separately). This module is not included in assembly because only users who still want to access HiveContext need it.
## How was this patch tested?
I manually tested `sbt/sbt -Phive package` and `mvn -Phive package -DskipTests`.
Author: Yin Huai <yhuai@databricks.com>
Closes#12580 from yhuai/compatibility.
