Links of links don't resolve properly

[stavro]

I have a blog post -> author -> image relationship. When requesting the blog post, both the author and images show up in the includes field in the resposne, but the resolve logic in this library doesn't flatten it out properly, and then image source is lost.

VCR'd Fixture: https://gist.github.com/stavro/fb38c303017549feb07e51f4b7665eb0

Expected: Be able to access the author's image.

Actual: Image is not available after this library parses the response. It is in the response though.

[WillRochaThomas]

@floriank should this issue be closed? I noticed the associated PR was, because this issue was based on old code?

[WillRochaThomas]

I think my PR will fix this for all types of links going forward #181