Support for nested serializers

Hi there,

Great tool! Are there any plans to support nested serializers? Like say:

``` python
class FooSerializer(serializers.Serializer):
spam = serializers.CharField()

class BarSerializer(serializers.Serializer):
foo = FooSerializer()
```

The endpoint for `BarSerializer` would list all the fields inside `FooSerializer`.

If you point me in the right direction, I can also take a look myself. Thanks again for making this tool.

Best,

Silvio

The issue names no files or tests. Start by locating how serializer fields are enumerated for endpoint output and trace the BarSerializer example with its nested FooSerializer. Done means the BarSerializer endpoint lists the fields inside FooSerializer, with coverage for the nested case.

Written by the indexing model from the issue text.