Bubble up router exceptions

@namusyaka I've been trying out this branch for a while now and it behaves very well :).

On this PR I'm letting the errors bubble up so that they're caught by Padrino itself -otherwise we don't get a stack trace or error logs at all.

The other point I'd like to review is how we're implementing Mustermann. First of all, [I don't think we should tie it to Rails like patterns](https://github.com/padrino/padrino-framework/blob/replace-with-new-router/padrino-core/lib/padrino-core/path_router.rb#L261). Since this change set will probably be released together with Sinatra 2.0, perhaps we're better off defaulting to [Sinatra 2.0 patterns](https://github.com/rkh/mustermann#sinatra)?
I also reckon we should allow for [options to be configured](https://github.com/rkh/mustermann#options). So maybe we can make those available through settings?

Thoughts @padrino/core-members?