Search by Room Category

* Update search logic in listing controller
* Add property category fields to forms
* Update the search results controller to grab array of properties

https://trello.com/c/8acKdgEO
We're already returning `result_set` at the end of this method, so maybe we can reverse this conditional and remove the `else`, so it matches the one above.

```
if search_params[:property_category].present?
  result_set = result_set.where( ... )
end
```