Send link as href in embedded object

[csantero]

According to the spec, sending a link should look like this:

{
    "posts": {
        "id": "2",
        "title": "How to fry an egg",
        "links": {
            "author": {
                "href": "/users/5"
            }
        }
    }
}

The formatter is currently sending:

{
    "posts": {
        "id": "2",
        "title": "How to fry an egg",
        "links": {
            "author": "/users/5"
        }
    }
}

There is no way for the client to tell that that is a link and not an ID. This PR changes the handling for [SerializeAs(SerializeAsOptions.Link)] to put the link on an href key in an embedded object.

I needed the json minifier helper from #8, so I included it here as a separate commit. I may need to rebase one of these PRs when you merge the other.

[SphtKr]

Crap, you're right...I wonder if the spec changed since I implemented that, but I see what you mean about why it needs to be discernable from an Id.

This will break previous behavior, so it will probably be helpful to go to 0.3.0 when this is put into a release.

[SphtKr]

Got #8 committed, so you should be able to rebase now.

[csantero]

All ready to go!

[SphtKr]

Ugh...for future reference, we should watch this issue, which would reverse this change.