Make password change asynchronous

This isn't perfect (if you make multiple requests things could go badly),
but it's better than just slapping the new password into the settings,
even if the update failed.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

qt-ui/preferences.h

@@ -40,6 +40,7 @@ slots:
 	void facebookLoggedIn();
 	void facebookDisconnect();
 	void cloudPinNeeded();
+	void passwordUpdateSuccessfull();
 private:
 	explicit PreferencesDialog(QWidget *parent = 0, Qt::WindowFlags f = 0);
 	void setUiFromPrefs();