WL#952: Installer should install MySQL as a service (optionally)

Affects: 3.4   —   Status: Complete   —   Priority: Low

The installer for Windows should install MySQL as a service when on
NT/2000/XP/2003 as an option, rather than having to install it by hand. This
installation should also deal with the 'upgrade' scenario, where MySQL is
already installed as a service.