use initialPosition on init

[rjruizes]

During initialization, setCenter is called twice:

1. by React, initialized to (0,0)
2. by InteractableView, initialized to the initialPosition

Occasionally, the second event is not received on the react-native side (#269). This PR makes the first event initialize to the initialPosition.

[chinmaygit]

When this PR is going to merge ?
looks like very important.

[rjruizes]

@rotemmiz Could you review please?

[alisherakb]

@rjruizes
When setting animatedNativeDriver={true} it gives an error:

AnimatedEvent is not a function (near '...})(event, gestureState ...')