Fixing problem: validation errors ignored on redirects. Closes #476

In conversation on Issue #476, @lucascs asked me to send this PR to start the bug fix.

Here the gist with the problematic controller as he asked me: [Problematic Controller](https://gist.github.com/renanigt/6f88e6fced50bce47ac9)
you can change this whole if on line 123 to:

```java
log.debug("Some validation errors occured: {}", getErrors());
```

slf4j already does the if internally.