Picker color on iOS

[aurelianv]

I was able to change the color on iOS of the Picker component only by setting the itemStyle property (with the color). I had to update the picker.js file on line 23 to this:
itemStyle: Text.propTypes.style,

[Callum Coombes]

I have also ended up doing the same. If you don't do this you end up with the error:
Warning: Failed prop type: Invalid props.itemStyle key 'color' supplied to 'Picker.'

This is because itemStyle is expecting ViewPropTypes.style