re-add Date.now shim for IE as it got lost in one of the merges
Modified latest version to work with NodeJS again.
Modified builder to apply changes for nodejs and create package folder.
Adds "proper" support for node.js

Merge branch 'nodejs-support-squashed' into dev

Conflicts:
	src/Tween.js
Added yoyo feature allowing you to reverse the tween when it reaches the end of the loop.
Move node.js/npm build stuff into utils/, also output npm package into build/npm (WIP)
bring change log up to date
Parenthesis >_<
Added unit test for yoyo functionality.
Added yoyo example.
Merge branch 'yoyo' of git://github.com/benjamind/tween.js into dev

Conflicts:
	build/tween.min.js
Fix property already defined, add Ben to contributors, update README / changelog