Update build system

[neocotic]

As part of the migration to JavaScript from CoffeeScript, (see #228) I would like to rewrite our Grunt-based build system using pure ECMAScript. I will also be removing the annotated source code (i.e. code documentation using generated by Docco).

The code will be bundled using something like rollup, webpack, or browserify so that dependencies can be require'd in the source files. The CSS will be bundled using LESS for #140.