Make this rev=2.4-beta-2, and turn rackspace https into beta.mathjax.org (this will need to be changed to cdn.mathjax.org for the final release).
Fix variable reference turned up by packer
Repack and recombine 2.4-beta-2
Switch beta.mathjax.org to cdn.mathjax.org (since https users will never get this beta MathJax.js anyway).