Text track selection support for iOS & ExoPlayer

Make sure Platforms get treated like they're on a newline

Refactor props docs

Add individual sections for each of the common configurable props

Preventing multiple observers for the same notification

Fixes #963

Fix partial swipe on video in fullscreen shows a black screen

In iOS 11, Apple added a feature to close the Video Player via a swipe gesture. Partial swiping cases viewWillDisappear to be called without viewDidDisappear which cases a black screen.

Link exoplayer with cookies

Use the client we create earlier in the function

Fix spacing