TableView improvements

[savelichalex]

Hi @asciiman! I did same iOS realisation by @talkol article, some times ago. And I have some questions about yours. Why you use observer instead setter for numRows? https://github.com/asciiman/react-native-native-listview/blob/master/ios/RNNativeListview.m#L54, in my code https://github.com/savelichalex/Souptitle/blob/master/apps/mobile/ios/STTableView.m#L58-L61. Also what you think about add some features like ListView direct scrolling https://github.com/savelichalex/Souptitle/blob/master/apps/mobile/ios/STTableView.m#L48-L51 and also onScroll event https://github.com/savelichalex/Souptitle/blob/master/apps/mobile/ios/STTableView.m#L142-L150 ?