Use same junit version for maven and sbt.

This makes sbt happy now that I put the junit assembly
in the shared dependencies in the root pom.

Author: Marcelo Vanzin

pom.xml

@@ -753,7 +753,7 @@
       <dependency>
         <groupId>junit</groupId>
         <artifactId>junit</artifactId>
-        <version>4.10</version>
+        <version>4.11</version>
         <scope>test</scope>
       </dependency>
       <dependency>

project/SparkBuild.scala

@@ -579,7 +579,6 @@ object TestSettings {
     testOptions in Test += Tests.Argument(TestFrameworks.JUnit, "-v", "-a"),
     // Enable Junit testing.
     libraryDependencies += "com.novocode" % "junit-interface" % "0.11" % "test",
-    libraryDependencies += "junit" % "junit" % "4.10" % "test",
     // Only allow one test at a time, even across projects, since they run in the same JVM
     parallelExecution in Test := false,
     // Make sure the test temp directory exists.