Ref #933 - dev and build tasks for Grunt

Dev: don't minify
Build: minify, lean Modernizr build

Dev assets will load if you have defined your WP_ENV as development
If you don't use Bedrock, you'll need to add this to your wp-config.php:

define('WP_ENV', 'development');

TODO: lib/scripts.php shouldn't need to be committed for changes after
running the version task