Initial support for map parameters

Closes #546 

Javadocs and tests will comming soon. Just to discuss the idea regarging parameters as Map.
@vitornp as Turini told, we only need default constructor for a managed beans. This class is not managed because have `@Vetoed` annotation, and we instantiate with `new` to create instances as you can see here: https://github.com/caelum/vraptor4/pull/677/files#diff-ac6ae891d48b200fe6c56de7d8dc126bR94