Added +parametersForURL: method

While messing with this library I found it could be useful to parse the URL for the parameters but without actually calling the routing blocks. This is similar to the `recongize_path` method in Rails.

In doing so I refactored one small thing, which is to pull the `pathComponents` array out of the `+routeURL:` method and stick it in the `-parametersForURL:` method. Seems like a better place for that logic, and this way it can be shared.

Let me know if this is useful or if you want me to change something.