Support dynamic routing (type coercion, regexp, named/unnamed wildcards)

[zachallaun]

Routes.jl currently supports only static routes. See spec-micro.jl for examples.

[despeset]

We should also make sure that a handler can be put at the end of an app to catch all unmatched requests. I guess this could either be a special route like "/*" or it could be a specific method like notfound( app, handler ).

Now that I think about it, I'm not clear on how we want to handle wildcard route matching in general... anybody have an idea about that?