Animations for transition on Android equal IPhone

### Version
Tell us which versions you are using:

- react-native-router-flux v4.0.6
- react v16.6.3
- react-native v0.57.8

### Expected behaviour

The same screen transition effect on iphone in android is possible and I have not found it.

### Actual behaviour

The same screen transition effect on iphone in android is possible and I have not found it.

### Steps to reproduce
For non-obvious bugs, please fork this component, modify Example project to reproduce your issue and include link here.
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### Reproducible Demo

Please provide a minimized reproducible demonstration of the problem you're reporting.

Issues that come with minimal repro's are resolved much more quickly than issues where a maintainer has to reproduce themselves.