Support webpack, jspm, and other bundlers

`browserify` is the only bundler that works out of box because of its dependency library, [glslify](https://github.com/stackgl/glslify), that uses browserify transforms. Browserify is great and all, but many of us already have our own favorite bundlers.

Please support `webpack`, `jspm`, and other popular bundlers by either dropping `glslify` from dependencies or adding `npm prepublish` script to pre-run `glslify`.

(Here's a [temporary workaround](https://gist.github.com/pilwon/1d054ed00350f5fea401) I'm currently using. The same script should work for all other bundlers too.)