Fix #330: Convert hash param to string

I was able to reproduce #330 ([here's the repo](https://github.com/rdickert/ir330_repro)). In summary, if the template contains

    <a href="{{pathFor 'customerList' hash=amountOwing}}"> View on customer list </a>

and `amountOwing` is an integer, the app will die with `TypeError: Object 3 has no method 'replace'`.

I added a failing test under `'Route - resolve'` and fixed it by calling `hash.toString()`.

This is my first PR to IR. Let me know if there is anything I should do differently - I'm learning here :-) I targeted the dev branch for this; not positive that's the correct one, so let me know.