[Don't merge yet] Update OSX and source downloads to rc2

Well, this is going to be an interesting git history.  The powers of `git pull --rebase` shine through once more!

@ihnorton once you've got builds for windows, feel free to send a PR to this PR, and we can merge it all in at once. (I'm assuming you'll be the one to do a windows build, as I don't yet have a good test setup ready for windows nightlies)