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!
This seems like an expensive operation, instead, I will recommend to build a collection of `dependants`, which is basically a list of modules that depends on the current module, and therefore any updates in the module should be propagated, this will work well with the circular dependencies as well.