add require dependency
add AMD support through require.js

This is a hybrid implementation that allows skrollr to be used with both AMD and global namespace
add AMD support

Please read the note related to exposing skrollr through require config. This patch allows for hybrid
usage as well (both AMD and global scope include). AMD version does not use DOMContentLoaded event -
require.js reference should be put at the bottom of your page's body
add fresh builds
add AMD version of the index page