Replace deprecated 'compile' gradle configuration with 'implementation'

[mars-lan]

See http://d.android.com/r/tools/update-dependency-configurations.html for more details

[hyochan]

@mars-lan Thank you for your PR. However, I wouldn't change this currently since react-native has default gradle version set to 3.1.4 which is not compatible with your changes. This can be merged when react-native android gradle version is upgraded to gradle version above 4.*. I think it would take long time since recent update has been made from 2->3.

[mars-lan]

I believe this is already the case for RN 0.57?

https://github.com/react-native-community/react-native-releases/blob/master/CHANGELOG.md#057

[hyochan]

@mars-lan Oh. I've missed that thank you. I will merge this!