vcsbase: auto save settings when requested by Core::ICore

Bazaar and Mercurial plugins are impacted

Change-Id: Ia781dae79983350d773f454de32f812e876bfbfb
Merge-request: 350
Reviewed-by: Tobias Hunger <tobias.hunger@nokia.com>
Reviewed-on: http://codereview.qt.nokia.com/645
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>

src/plugins/mercurial/optionspage.cpp

@@ -125,8 +125,7 @@ void OptionsPage::apply()
     if (newSettings != plugin->settings()) {
         //assume success and emit signal that settings are changed;
         plugin->setSettings(newSettings);
-        newSettings.writeSettings(Core::ICore::instance()->settings(),
-                                  QLatin1String("Mercurial"));
+        newSettings.writeSettings(Core::ICore::instance()->settings());
         emit settingsChanged();
     }
 }