Adds the ability to include the user pin in the zoom_to_fit_annotations method

Nice for zooming into all annotations PLUS the user to fit the screen.

This should always be called after you know you have a user location on the screen, most likely inside the `on_user_location(location)` method. Otherwise, it ignores the user's location since it's still `nil`.
I tend to like option hashes (you've probably noticed) since they self-document on the app side.

```ruby
zoom_to_fit_annotations(true, true)
# vs
zoom_to_fit_annotations(true, include_user: true)
# or even better (but this breaks the API):
zoom_to_fit_annotations(animated: true, include_user: true)
```

```ruby

```