Added a simple GruntJS

Added my GruntJS script for rapid development of pure JavaScript
projects. The Grunt script automatically adds script tags to the
index.html file, automatically reloads browser and JSHints the
JavaScript files. It can also minify all JS files and deploy them to a
build folder.

The app itself is rather unimpressive though, it simply draws a black
rectangle using WebGL.

I included the WebGL library files used by the "WebGL Programming Guide"
book.