Add ability to switch themes without having to use Executions.sendRedirect(null);

Currently the only way to switch themes is by setting the cookie value and calling
Executions.sendRedirect(null);

While this may work well in situations where each page has a distinct URL, this doesn't work very nicely in multi-windowed app. If a user has logged in to the app and multiple windows have been created via createComponents(...), sending the redirect reloads the app and requires the user to re-login and open the windows again.