v0.5.1 support for PATCH

With patch (add specifically) you're just supposed to spit out the changed object. 

http://jsonapi.org/format/#patch-responses-200

Since we're ignoring the recentGames: ... side of things (ie `/users/me/links/recentGames` if it existed wouldn't start with:

```
{
  recentGames: ...
}
```

and instead just be the `...`

we'd really just be returning the value that was added, inside of an array (since it supports multiple operations)