[SPARK-6118] making package name of deploy.worker.CommandUtils and...

[SPARK-6118] making package name of deploy.worker.CommandUtils and deploy.CommandUtilsSuite consistent

https://issues.apache.org/jira/browse/SPARK-6118

I found that the object CommandUtils is placed under deploy.worker package, while CommandUtilsSuite is  under deploy

Conventionally, we put the implementation and unit test class under the same package

here, to minimize the change, I move CommandUtilsSuite to worker package,

**However, CommandUtils seems to contain some general methods (though only used by worker.* classes currently**,  we may also consider to replace CommonUtils

Author: CodingCat <zhunansjtu@gmail.com>

Closes #4856 from CodingCat/SPARK-6118 and squashes the following commits:

cb93700 [CodingCat] making package name consistent

core/src/test/scala/org/apache/spark/deploy/CommandUtilsSuite.scala → core/src/test/scala/org/apache/spark/deploy/worker/CommandUtilsSuite.scala

@@ -15,11 +15,10 @@
  * limitations under the License.
  */
 
-package org.apache.spark.deploy
+package org.apache.spark.deploy.worker
 
-import org.apache.spark.deploy.worker.CommandUtils
+import org.apache.spark.deploy.Command
 import org.apache.spark.util.Utils
-
 import org.scalatest.{FunSuite, Matchers}
 
 class CommandUtilsSuite extends FunSuite with Matchers {