Fix Greboid-induced NPE in fdnotify plugin

Fixes issue 3517

Change-Id: Ia8c3cd8a4bedeaced1c61aee0121450c6663212f
Reviewed-on: http://gerrit.dmdirc.com/514
Automatic-Compile: Gregory Holmes <greboid@dmdirc.com>
Reviewed-by: Gregory Holmes <greboid@dmdirc.com>

src/com/dmdirc/addons/freedesktop_notifications/FreeDesktopNotificationsPlugin.java

@@ -71,9 +71,6 @@ public final class FreeDesktopNotificationsPlugin extends Plugin implements
      */
     public FreeDesktopNotificationsPlugin() {
         super();
-
-        IdentityManager.getGlobalConfig().addChangeListener(getDomain(), this);
-        setCachedSettings();
     }
 
     /**
@@ -145,6 +142,9 @@ public final class FreeDesktopNotificationsPlugin extends Plugin implements
      */
     @Override
     public void onLoad() {
+        IdentityManager.getGlobalConfig().addChangeListener(getDomain(), this);
+        setCachedSettings();
+
         command = new FDNotifyCommand(this);
 
         // Extract required Files
@@ -181,6 +181,7 @@ public final class FreeDesktopNotificationsPlugin extends Plugin implements
     @Override
     public synchronized void onUnload() {
         CommandManager.unregisterCommand(command);
+        IdentityManager.getGlobalConfig().removeListener(this);
     }
     
     /** {@inheritDoc} */