In the javascript editor, '$' characters were getting stomped on when
trying to remove backreferences after doing transformations on text
(Bolding, Italicizing, etc.).  This can be fixed by first escaping the
string to be transformed and then unescaping it afterwards.
Merge pull request #805 from MrJaeger/respect-dollar-signs

Allow for $ characters on front-end editor
Fix MathJax CDN URL

According to the [MathJax Blog](http://www.mathjax.org/changes-to-the-mathjax-cdn/), MathJax will retire the `rackcdn` CDN address at the end of this month. Updated the script to used the new CDN URL, and also made it so that the URL is HTTP/HTTPS agnostic, following the [MathJax docs](http://docs.mathjax.org/en/latest/start.html#secure-access-to-the-cdn).
Merge pull request #841 from marcusps/mathjax-cdn-fix

Fix MathJax CDN URL
Merge remote-tracking branch 'upstream/master'
update .rvmrc