Added Grunt task runner.

Grunt tasks:

         clean  Clean files and folders.
        concat  Concatenate files.
        jshint  Validate files with JSHint.
          sass  Compile Sass to CSS
        uglify  Minify files with UglifyJS.
       default  Does nothing.
            js  Concat and minify JavaScript.
          lint  Alias for "jshint" task.
          hint  Alias for "jshint" task.

Moved 'public/scss' to 'public/sass' and JS sources in 'public/js/src'.

To create JS and CSS files, run:

grunt js
grunt sass
Ignore JS and CSS files.
Ignore .sass-cache folder.
Fixed refs to resources.
Updated docs for tasks.
Minimalism.
Fixed npm warning about repository field.
Added grunt-modernizr.
Updated Travis file to install npm packages.
Grunt task for custom Modernizr builds.

`grunt modernizr` or `grunt js`

The latter will run the Modernizr builds and some.
Added Grunt build task.
Don't diff minified JS.