Removed mediaSession related things

A little fix of video resuming while entering pip mode.

Entering PIP mode on leave is now PROP driven + Unregistering receivers.

Added PR link into the changelog

# Conflicts:
#	CHANGELOG.md
#	android-exoplayer/build.gradle
#	android-exoplayer/src/main/java/com/brentvatne/exoplayer/ReactExoplayerView.java
#	package.json

readme change

ReadMe + changelog

Added mediaSession extension to enable PIP controls.

Added another receiver 

fix typo in README

Added a PIP support for Android

- Bump Exoplayer to 2.10.4
- Remove deprecated usages of Exoplayer methdos
- Add `ReactExoplayerConfig` as extension points to configure the Exoplayer instance

Fixed Exoplayer doesn't work with mute=true #1696

Added support for automaticallyWaitsToMinimizeStalling property on iOS 

Removing the call to observeValueForKeyPath:ofObject:change:context: …

Updated README.md to include instructions for React Native 0.60 and a…

[FIX] Fix release 5.0.0 bad merge with 5.0.1

fix crash iOS9

If the super class is not actually observing the key, the app will crash. Checking to see if
the super class responds to this selector doesn't solve this issue.

react-native-video github issue: https://github.com/react-native-community/react-native-video/issues/1515

Discussion about this particular problem: https://stackoverflow.com/questions/6574714/whats-wrong-with-this-observevalueforkeypathofobjectchangecontext-implement