ListView contents disappear occasionally when popping from the Navigator stack

[mattyu007]

On some screens with ListView components, popping to the screen will result in a blank ListView being displayed until the list is scrolled.

Probably related to the known RN issue https://react-native.canny.io/feature-requests/p/listview-doesnt-render-rows-until-scroll, but in the meantime, we may want to evaluate setting the removeClippedSubviews prop to false to work around the issue.

[mattyu007]

Should be closed by #199. We should monitor scroll performance to ensure it hasn't regressed tremendously.