suppress old pre-Final/pre-GA milestones from the downloads overview page

Recently I commented out a lot of old releases because they're old.

But as a result the what's new page [1] now shows a ton of old milestones as coming soon.

So we either need to hide old milestones from the what's new page, or find a way to suppress builds from appearing on the downloads page [2].

[1] http://tools.jboss.org/documentation/whatsnew/
[2] http://tools.jboss.org/downloads/overview.html