Remove enabling key for JunitXmlReportPlugin.

This migrates JunitXmlReportPlugin to work the way we desire
new sbt features/plugins to work:

* Enabling the feature is having the plugin available.
* Disabling the feature is disabling the plugin
* All code/settings for the feature are isolated to the plugin.

main/src/main/scala/sbt/Keys.scala

@@ -195,7 +195,6 @@ object Keys
 	val testFrameworks = SettingKey[Seq[TestFramework]]("test-frameworks", "Registered, although not necessarily present, test frameworks.", CTask)
 	val testListeners = TaskKey[Seq[TestReportListener]]("test-listeners", "Defines test listeners.", DTask)
 	val testForkedParallel = SettingKey[Boolean]("test-forked-parallel", "Whether forked tests should be executed in parallel", CTask)
-	val testReportJUnitXml = SettingKey[Boolean]("test-report-junit-xml", "Produce JUnit XML test reports", BPlusTask)
 	val testExecution = TaskKey[Tests.Execution]("test-execution", "Settings controlling test execution", DTask)
 	val testFilter = TaskKey[Seq[String] => Seq[String => Boolean]]("test-filter", "Filter controlling whether the test is executed", DTask)
 	val testResultLogger = SettingKey[TestResultLogger]("test-result-logger", "Logs results after a test task completes.", DTask)

main/src/main/scala/sbt/plugins/JUnitXmlReportPlugin.scala

@@ -6,13 +6,14 @@ import Keys._
 import Project.inConfig
 import Configurations.Test
 
-/** A plugin that adds the ability for junit-xml to be generated.
+/** An experimental plugin that adds the ability for junit-xml to be generated.
  *
- *  While this plugin automatically includes its settings, to enable, you need to
- *  add:
+ *  To disable this plugin, you need to add:
  *  {{{
- *     testReportJunitXml in Global := true
+ *     val myProject = project in file(".") disablePlugins (plugins.JunitXmlReportPlugin)
  *  }}}
+ *
+ *  Note:  Using AutoPlugins to enable/disable build features is experimental in sbt 0.13.5.
  */
 object JUnitXmlReportPlugin extends AutoPlugin {
   // TODO - If testing becomes its own plugin, we only rely on the core settings.
@@ -23,13 +24,6 @@ object JUnitXmlReportPlugin extends AutoPlugin {
   // It might be a good idea to derive this setting into specific test scopes.
   override lazy val projectSettings: Seq[Setting[_]] =
     Seq(
-      testListeners ++= (if( testReportJUnitXml.value ) Seq(new JUnitXmlTestsListener(target.value.getAbsolutePath)) else Nil)
+      testListeners += new JUnitXmlTestsListener(target.value.getAbsolutePath)
     )
-  override lazy val globalSettings: Seq[Setting[_]] =
-    Seq(
-      // TODO - in sbt 1.0, this should default to true.
-      testReportJUnitXml :== false
-    )
-
-  override def projectConfigurations: Seq[Configuration] = Seq()
 }

sbt/src/sbt-test/tests/junit-xml-report/project/JUnitXmlReportTest.scala

@@ -15,8 +15,6 @@ object JUnitXmlReportTest extends Build {
 		scalaVersion := "2.9.2",
 		libraryDependencies += "com.novocode" % "junit-interface" % "0.10" % "test",
 
-		testReportJUnitXml := true,
-
 		// TODO use matchers instead of sys.error
 		checkReport := {
 			val oneSecondReport = XML.loadFile(oneSecondReportFile)