return user content in summary view - closes #62

see #62 

example return value:

```json
{
  "id": "23",
  "parcelId": "131P A 029.01",
  "address": "4814 BLUE BELL AVE",
  "city": "HAMILTON COUNTY",
  "state": "TN",
  "data": {
    "owner": {
      "id": "undefined",
      "href": "http://localhost:9001/landlords/undefined"
    },
    "violations": {
      "href": "http://localhost:9001/homes/23/violations",
      "summary": [],
      "count": 0
    },
    "comments": [],
    "userContent": {
      "cats": "true"
    }
  }
}
```

if a home has no user contributed content, it will return an empty object:
```json
{
  "id": "23",
  "parcelId": "131P A 029.01",
  "address": "4814 BLUE BELL AVE",
  "city": "HAMILTON COUNTY",
  "state": "TN",
  "data": {
    "owner": {
      "id": "undefined",
      "href": "http://localhost:9001/landlords/undefined"
    },
    "violations": {
      "href": "http://localhost:9001/homes/23/violations",
      "summary": [],
      "count": 0
    },
    "comments": [],
    "userContent": {}
  }
}
```