Allow for dynamic URI patterns with named parameters

Parsing of these should be as simple as possible, so the placeholders should be delimited by some URI-invalid character (e.g. `{}`) and later on differentiated from each other by some identifying string pattern at the beginning of the character sequence (e.g. `{@myvar}`, `{?myothervar}`).

``` yaml
'/myroute/{@dynamicPart}': '/{@dynamicPart}/myotherroute'
```
