JCenter issue.

Hello @arpruss 

During gradle of application i am getting 2 library issue which is not found.

```
Could not find com.google.android.exoplayer:exoplayer-core:2.11.1.
Could not find com.google.android.exoplayer:extension-okhttp:2.11.1.
Could not find me.toptas.fancyshowcase:fancyshowcaseview:1.3.0.
```

is there any alternative for this or hive you fix it?

Thanks 🙂