报错：'Navigator is deprecated and has been removed from this package. It
can now be installed ' + 'and imported from `react-native-deprecated-
custom-components` instead of `react-native`. ' + 'Learn about alternative
navigation solutions at http://facebook.github.io/react-native/docs/navigation.html'
这是因为版本升级到0.43以上的话，Navigator不能直接从react-native里面获取了，
解决方案：
npm install react-native-deprecated-custom-components
--save
然后在引用的地方
import {Navigator}
from react-native-deprecated-custom-components
