Updated for 0.6.5 - modified Tween.js source to attach it to window

Due to Meteor's variable scoping, anything declared as `var` in the top level cannot be seen outside the file.

`TWEEN` is defined just like this in `Tween.js`, so I have attached it to the window object to export it. Also this makes it client only, I'm not sure if you deliberately wanted to make it both server and client.

See https://groups.google.com/forum/#!topic/meteor-talk/R_wGMDics9g for more information on the var 3rd party problem.