WIP: angular + universal module definition

Here is a WIP at making angular work with UMD (based on [this format](https://github.com/umdjs/umd/blob/master/returnExports.js)).

I did not attempt to remove angular from the window. That's a bigger project; so much of the internals rely on window.angular. Instead I just made angular export itself as a define/module.exports in addition to the window.

I still don't know how to test the umd code, since the tests don't concatenate the code and don't work on *.prefix and *.suffix files.  

I thought of moving the UMD code out of `angular.prefix`/`module.prefix` and into the code somewhere - but don't know where.  Feedback is welcome :-)