[Pharo-project] Updated pharo.org: point to current VMs

Hi, To prepare the release, I have changed http://www.pharo-project.org/pharo-download/beta-2-0 to point to the latest VMs. With the release, the then current build will be the one for 2.0 and hard-coded (to avoid a constant changing VM). To be updated again for 2.1. Marcus