autoupdate: integrate winsparkle

- Winsparkle is the windows port of Sparkle the framework used on OSX
to provide the autoupdate feature
- This commit add:
  - Winsparkle as a submodule
  - A check for update button in the configuration panel
  - All that is guarded by ENABLE_AUTOUPDATE to allow build without
  Winsparkle
  - Add a way for the user to enable/disable auto check for updates
  and to set the interval of these checks

Change-Id: Iea9cb0a31b60c8111f30a4f648d6f5e80b92abdc
Tuleap: #183
diff --git a/configurationwidget.h b/configurationwidget.h
index ba3c928..4af55e4 100644
--- a/configurationwidget.h
+++ b/configurationwidget.h
@@ -56,6 +56,9 @@
     void on_clearHistoryButton_clicked();
     void on_historyDaySettingsSpinBox_valueChanged(int limit);
     void on_closeOrMinCheckBox_toggled(bool checked);
+    void on_checkUpdateButton_clicked();
+    void on_autoUpdateCheckBox_toggled(bool checked);
+    void on_intervalUpdateCheckSpinBox_valueChanged(int arg1);
 
 private slots:
     void accountSelected(QItemSelection itemSel);