can not serialize guava Iterables

In 2.4.1.3 this works

``` java
new ObjectMapper().writeValueAsString(new Iterable<Integer>() {
  @Override
  public Iterator<Integer> iterator() {
    return ImmutableList.of(1, 2, 3).iterator();
  }
});
```

but this  doesn't.

``` java
new ObjectMapper().writeValueAsString(Iterables.limit(Iterables.cycle(1,2,3), 3));
```
