tapBackgroundToDismiss property on screen API (#3012)

This is working on the screen API too, however it's not included in screen API, only on top-level screen

docs/screen-api.md

@@ -114,7 +114,8 @@ this.props.navigator.showLightBox({
  passProps: {}, // simple serializable object that will pass as props to the lightbox (optional)
  style: {
    backgroundBlur: "dark", // 'dark' / 'light' / 'xlight' / 'none' - the type of blur on the background
-   backgroundColor: "#ff000080" // tint color for the background, you can specify alpha here (optional)
+   backgroundColor: "#ff000080", // tint color for the background, you can specify alpha here (optional)
+   tapBackgroundToDismiss: true // dismisses LightBox on background taps (optional)
  },
  adjustSoftInput: "resize", // android only, adjust soft input, modes: 'nothing', 'pan', 'resize', 'unspecified' (optional, default 'unspecified')
 });