Fix Android audio crash fixes Issue #1417

Why:

* There is a case where groupIndex may be unset

This change addresses the need by:

* Don't chain check for INDEX_UNSET to previous conditional

1319 - fullscreen rotation issues with iOS built-in controls

Fix tvOS picture-in-picture compilation regression.

Adding compileOptions Java 1.8 to build.gradle

fix: access on undefined variable

Implement picture in picture for iOS

Instead of crashing, show a warning and return

Throw an error instead of crashing app when video source is empty

fix: remove runtime warning by replacing `UIManager.RCTVideo` with `UIManager.getViewManagerConfig('RCTVideo')` (and ensuring backwards compat) (#1487)

* replaced UIManager.RCTVideo >  UIManager.getViewManagerConfig('RCTVideo')

* added requested changes

* updated changelog.md

* docs: adjust wording

* fix(ios): message sent to deallocated instance

* chore: update changelog

If an undefined source is accidentally loaded in react-native-video a fatal error SIGABRT will happen and crash the application. This is very difficult to debug since there's apparently no relation between this crash and react-native-video. So this change checks if the URI is empty and, if it is, it throws an error, allowing the user to find out early about the issue.

https://cloud.githubusercontent.com/assets/5795227/20283860/08223ba6-aabb-11e6-9fdc-d12d32b3aa9a.png

Feature Implementation: Recovery from transient internet failures

I'm guessing this change was made to cleanup the code, however it is not functionally identical and may cause issues. Revert until those can be discussed.

Support for displaying controls in Android Exoplayer