Add support for auto-complete API

We've been using this for auto-complete support when using the Google Places API. 

Let me know how you feel about naming and if there is anything else that we can update to facilitate brining this is as part of the project.

```ruby
client = GooglePlaces::Client.new ENV['GOOGLE_PLACES_API_KEY']
client.predictions_by_input(
      'San F',
      lat: 0.0,
      lng: 0.0,
      radius: 20000000,
      types: 'geocode',
      language: I18n.locale,
)
```