Protected Areas API

Creates a API to query by wdpa_id (to feed third party projects on protected-planet-consumer)

The query can be done using:

http://localhost:3000/api/protected_areas?wdpa_id=[wdpa_id]

You can check the code on

controllers/api/protected_areas.rb
models/protected_areas.rb
test/integration/api_test.rb

Once the routes are changed, as below, you should change this method to `def show`: we are doing it more like The Rails Way™.

This method will stay pretty much the same, but instead of adding to `@protected_areas` hash, you'd do something like:

```
@protected_area = ProtectedArea.without_geometry.where('wdpa_id = ?', params[:id]).first
render json: @protected_area
```