System.register update

This includes the System.register update corresponding to the new format implemented into Traceur here - https://github.com/google/traceur-compiler/pull/1161.

All tests are passing!
it is not a big deal to use `__global` here since that's a controlled code, but I will recommend to use the same context used for the executed, which is going to be the weird metamodule object ;), anyway, we are good for now.