[SPARK-6694][SQL]SparkSQL CLI must be able to specify an option --database on the command line.

SparkSQL CLI has an option --database as follows.
But, the option --database is ignored.

```
$ spark-sql --help
:
CLI options:
    :
    --database <databasename>     Specify the database to use
```

Author: Jin Adachi <[email protected]>
Author: adachij <[email protected]>

Closes apache#5345 from adachij2002/SPARK-6694 and squashes the following commits:

8659084 [Jin Adachi] Merge branch 'master' of https://github.com/apache/spark into SPARK-6694
0301eb9 [Jin Adachi] Merge branch 'master' of https://github.com/apache/spark into SPARK-6694
df81086 [Jin Adachi] Modify code style.
846f83e [Jin Adachi] Merge branch 'master' of https://github.com/apache/spark into SPARK-6694
dbe8c63 [Jin Adachi] Change file permission to 644.
7b58f42 [Jin Adachi] Merge branch 'master' of https://github.com/apache/spark into SPARK-6694
c581d06 [Jin Adachi] Add an option --database test
db56122 [Jin Adachi] Merge branch 'SPARK-6694' of https://github.com/adachij2002/spark into SPARK-6694
ee09fa5 [adachij] Merge branch 'master' into SPARK-6694
c804c03 [adachij] SparkSQL CLI must be able to specify an option --database on the command line.

Author: adachij2002

sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala

@@ -145,6 +145,9 @@ private[hive] object SparkSQLCLIDriver {
       case e: UnsupportedEncodingException => System.exit(3)
     }
 
+    // use the specified database if specified
+    cli.processSelectDatabase(sessionState);
+
     // Execute -i init files (always in silent mode)
     cli.processInitFiles(sessionState)
 

sql/hive-thriftserver/src/test/scala/org/apache/spark/sql/hive/thriftserver/CliSuite.scala

@@ -25,22 +25,31 @@ import scala.concurrent.{Await, Promise}
 import scala.sys.process.{Process, ProcessLogger}
 
 import org.apache.hadoop.hive.conf.HiveConf.ConfVars
-import org.scalatest.{BeforeAndAfterAll, FunSuite}
+import org.scalatest.{BeforeAndAfter, BeforeAndAfterAll, FunSuite}
 
 import org.apache.spark.Logging
 import org.apache.spark.util.Utils
 
-class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
+class CliSuite extends FunSuite with BeforeAndAfter with Logging {
+  val warehousePath = Utils.createTempDir()
+  val metastorePath = Utils.createTempDir()
+
+  before {
+      warehousePath.delete()
+      metastorePath.delete()
+  }
+
+  after {
+      warehousePath.delete()
+      metastorePath.delete()
+  }
+
   def runCliWithin(
       timeout: FiniteDuration,
       extraArgs: Seq[String] = Seq.empty)(
-      queriesAndExpectedAnswers: (String, String)*) {
+      queriesAndExpectedAnswers: (String, String)*): Unit = {
 
     val (queries, expectedAnswers) = queriesAndExpectedAnswers.unzip
-    val warehousePath = Utils.createTempDir()
-    warehousePath.delete()
-    val metastorePath = Utils.createTempDir()
-    metastorePath.delete()
     val cliScript = "../../bin/spark-sql".split("/").mkString(File.separator)
 
     val command = {
@@ -95,8 +104,6 @@ class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
          """.stripMargin, cause)
       throw cause
     } finally {
-      warehousePath.delete()
-      metastorePath.delete()
       process.destroy()
     }
   }
@@ -124,4 +131,24 @@ class CliSuite extends FunSuite with BeforeAndAfterAll with Logging {
   test("Single command with -e") {
     runCliWithin(1.minute, Seq("-e", "SHOW DATABASES;"))("" -> "OK")
   }
+
+  test("Single command with --database") {
+    runCliWithin(1.minute)(
+      "CREATE DATABASE hive_test_db;"
+        -> "OK",
+      "USE hive_test_db;"
+        -> "OK",
+      "CREATE TABLE hive_test(key INT, val STRING);"
+        -> "OK",
+      "SHOW TABLES;"
+        -> "Time taken: "
+    )
+
+    runCliWithin(1.minute, Seq("--database", "hive_test_db", "-e", "SHOW TABLES;"))(
+      ""
+        -> "OK",
+      ""
+        -> "hive_test"
+    )
+  }
 }