Update less.jsm

The location of the less file (https://raw.githubusercontent.com/cloudhead/less.js/master/dist/less-1.3.3.js) was throwing a java.io.FileNotFoundException because the cloudhead/less.js repository has apparently gone away. (curl https://raw.githubusercontent.com/cloudhead/less.js/master/dist/less-1.3.3.js ->
Not Found)

I don't know if there is a better place to get the file, but this CDN location works and allows the project to build