Page annotation does not work when declared in the super class

In FluentTest subclasses the fields annotated with Page annotation are only instantiate in the top level class.

How to reproduce the bug:

```
class ATest extends FluentTest {
    @page public FirstPage first;
    /* ... */
}

class BTest extends ATest {
    @Test
    public void a_test() {
        goTo(first);  /* Throws a NullPointerException */
    }
}
```

This patch loops on the test class (up to `FluentAdapter`) and instantiate all found `FluentPage` objects.