User generated save - closes #42

- adds a userGeneratedContent service
- adds http endpoint add http endpoint at POST /homes/:id/data
- adds unit tests
- adds curl http tests

lmk if you have questions :)
These are properties in relation to a thing, where the thing is a subject - in this case, the home whose id is in the route parameter.

So, it's modeled as, for example,
```
subject ---   rel   --- value
$house --- lease --- year 
```

And yes, the way this is implemented would mean making 3 api requests for 3 questions answered. If it becomes an issue, we can look at batching them.