Make compatible with SystemJS locate

[mavericken]

Currently, when a SystemJS plugin makes use of locate to find an alternate path to a file, the address does not match the loader name, so hot reload does not work.

I have included a pull request to check for address also, so that such cases should work.

#114

[mavericken]

Well that was awkward... My merge failed spectacularly because the code I was changing was refactored out to https://github.com/alexisvincent/systemjs-hmr

I'll relocate this effort over there.