Add JSON versioning capability

This PR add JSON versioning capability to VRaptor4.
One of the most strategies used for API versioning is through URI. 
With this PR, one can do API versioning allowing the controller to build a result based on URI parameter. 

A sample example of usage follows:
```java
@Get("/example/{version}")
public void example(String version) {
	Object response = new Object();
	result.use(Results.json()).version(version).from(response).serialize();
}
```

@adolfoweloy @andrelrs 
I think that we need to implements the same behavior from Gson. If Gson always shows elements without `Since` annotation, we need to keep this behavior. The condition `f.getAnnotation(Since.class) == null` means that members without `Since` will be skiped. But Gson behavior is members without annotation will serialized.

@Turini what you think?