Stage 1 : Create hudson.model.Jenkins, make Hudson derive from Jenkins.

Signed-off-by: Nigel Magnay <nigel.magnay@gmail.com>

core/src/main/java/hudson/Plugin.java

@@ -23,7 +23,7 @@
  */
 package hudson;
 
-import hudson.model.Hudson;
+import hudson.model.Jenkins;
 import hudson.model.Descriptor;
 import hudson.model.Saveable;
 import hudson.model.listeners.ItemListener;
@@ -100,7 +100,7 @@ public abstract class Plugin implements Saveable {
      *
      * <p>
      * This method is called after {@link #setServletContext(ServletContext)} is invoked.
-     * You can also use {@link Hudson#getInstance()} to access the singleton hudson instance,
+     * You can also use {@link hudson.model.Jenkins#getInstance()} to access the singleton hudson instance,
      * although the plugin start up happens relatively early in the initialization
      * stage and not all the data are loaded in Hudson.
      *
@@ -242,8 +242,8 @@ public abstract class Plugin implements Saveable {
      * @since 1.245
      */
     protected XmlFile getConfigXml() {
-        return new XmlFile(Hudson.XSTREAM,
-                new File(Hudson.getInstance().getRootDir(),wrapper.getShortName()+".xml"));
+        return new XmlFile(Jenkins.XSTREAM,
+                new File(Jenkins.getInstance().getRootDir(),wrapper.getShortName()+".xml"));
     }