Search author data

Note: This pull request is based on top of #98

Search used to return data like this: (e.g. http://localhost:6543/search?q="college+physics")

```
{
    "query": {
        "sort": [],
        "limits": [{
            "text": "college physics"
        }]
    },
    "results": {
        "items": [{
            ...
            "authors": [{
                "website": null,
                "surname": null,
                "suffix": null,
                "firstname": "OpenStax College",
                "title": null,
                "othername": null,
                "email": "info@openstaxcollege.org",
                "fullname": "OpenStax College",
                "id": "e5a07af6-09b9-4b74-aa7a-b7510bee90b8"
            }],
            "id": "209deb1f-1a46-4369-9e0d-18674cf58a3e",
            "mediaType": "Module"
        },
        {
            ...
            "authors": [{
                "website": null,
                "surname": null,
                "suffix": null,
                "firstname": "OpenStax College",
                "title": null,
                "othername": null,
                "email": "info@openstaxcollege.org",
                "fullname": "OpenStax College",
                "id": "e5a07af6-09b9-4b74-aa7a-b7510bee90b8"
            }],
            "id": "e79ffde3-7fb4-4af3-9ec8-df648b391597",
            "mediaType": "Collection"
        }],
        "total": 2,
        "limits": [{
            "count": 2,
            "pubYear": "2013"
        },
        {
            "count": 2,
            "author": "e5a07af6-09b9-4b74-aa7a-b7510bee90b8"
        },
        {
            "count": 1,
            "mediaType": "application/vnd.org.cnx.collection"
        },
        ...
      ]
   }
}
```

Now, author data in search limits is expanded but in search result items we're only showing the id. (e.g. http://localhost:6543/search?q="college+physics")

```
{
    "query": {
        "sort": [],
        "limits": [{
            "text": "college physics"
        }]
    },
    "results": {
        "items": [{
            ...
            "authors": ["e5a07af6-09b9-4b74-aa7a-b7510bee90b8"],
            "id": "209deb1f-1a46-4369-9e0d-18674cf58a3e",
            "mediaType": "Module"
        },
        {
            ...
            "authors": ["e5a07af6-09b9-4b74-aa7a-b7510bee90b8"],
            "id": "e79ffde3-7fb4-4af3-9ec8-df648b391597",
            "mediaType": "Collection"
        }],
        "total": 2,
        "limits": [{
            "count": 2,
            "pubYear": "2013"
        },
        {
            "count": 2,
            "author": {
                "website": null,
                "surname": null,
                "suffix": null,
                "firstname": "OpenStax College",
                "title": null,
                "othername": null,
                "email": "info@openstaxcollege.org",
                "fullname": "OpenStax College",
                "id": "e5a07af6-09b9-4b74-aa7a-b7510bee90b8"
            }
        },
        {
            "count": 1,
            "mediaType": "application/vnd.org.cnx.collection"
        },
        ...
    ]
  }
}
```