Introduce IPlugin#shutdown.

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/Plugins.kt

@@ -47,6 +47,8 @@ class Plugins @Inject constructor (val taskManagerProvider : Provider<TaskManage
         fun findPlugin(name: String) : IPlugin? = pluginMap[name]
     }
 
+    fun shutdownPlugins() = plugins.forEach { it.shutdown() }
+
     fun applyPlugins(context: KobaltContext, projects: List<Project>) {
         plugins.forEach { plugin ->
             addPluginInstance(plugin)

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/api/BasePlugin.kt

@@ -12,6 +12,8 @@ abstract class BasePlugin : IPlugin {
         this.context = context
     }
 
+    override fun shutdown() {}
+
     override lateinit var taskManager: TaskManager
     lateinit var plugins: Plugins
 }

modules/kobalt-plugin-api/src/main/kotlin/com/beust/kobalt/api/IPlugin.kt

@@ -2,9 +2,29 @@ package com.beust.kobalt.api
 
 import com.beust.kobalt.internal.TaskManager
 
-public interface IPlugin : IPluginActor {
+interface IPlugin : IPluginActor {
+    /**
+     * The name of this plug-in.
+     */
     val name: String
+
+    /**
+     * @return true if this plug-in decided it should be enabled for this project.
+     */
     fun accept(project: Project) : Boolean
+
+    /**
+     * Invoked on all plug-ins before the Kobalt execution stops.
+     */
+    fun shutdown()
+
+    /**
+     * Main entry point for a plug-in to initialize itself based on a project and a context.
+     */
     fun apply(project: Project, context: KobaltContext) {}
+
+    /**
+     * Injected by Kobalt to manage tasks.
+     */
     var taskManager : TaskManager
 }