fix(RCTVideo.m): Fixed status bar disappearing issue

This is related to the comment on #368

Before, when you resumed the app the player would **always** start playing again.

After this changed the `paused` prop of the `Video` component (which is the `isPaused` variable internally)
is consulted on resume for whether or not the playback should resume as well.

* added listener for timedMetadata event.

* added callback in RCTVideo for the timed metadata

* exposing onTimedMetadata to JS

* added forgotten method declaration

* returning array of string values

* added metadata type to the array

* added onMetadata method

* overridden onMetadata method on exoplayer2

* added format of return value from onMetadata

* added function reference in README file

Corrected the instructions for running the example

* Fix require(...) file resource on Android production

* Update example (use require for ./broadchurch.mp4)

* Fix MainApplication.java of example

* Add default source type

- Use NSNull object in NSDictionary when type (or URI) missing from supplied
  src object.
- In addition, defensively supply valid strings for URI and type from JS.

The transform matrix was not being recalculated when the View
dimensions changed. Fixed by copying the code from the scaleVideoSize
method from the ScalableVideoView.

https://github.com/yqritc/Android-ScalableVideoView/blob/master/library/src/main/java/com/yqritc/scalablevideoview/ScalableVideoView.java#L95

* Support react-native > 0.40

* Bumping major version. Breaking change.

* Upgrade example project from 0.33 => 0.40.

When directory structure was refactored, source files were moved to `ios/` dir, but the podspec wasn't updated to reflect this.

* offered html5-like poster attribute

* prevent unnecessary setState

feat(Windows): Adds Windows support to react-native-video

This PR adds react-native-windows support to react-native-video.  The Video component is implemented with a XAML MediaPlayerElement.  Most of the features implemented by Android (and some additional ones) are implemented by Windows.

Known issues and missing features include:
* onReadyForDisplay event
* local URI convention (e.g., "broadchurch" in examples changed to require("./broadchurch.mp4")
* `playableDuration` in `onVideoProgress` event is always 0.0
* `playInBackground` is not yet supported
* Volume settings are applied, but the UWP control does not handle it properly

* BUGFIX. Progress Update Handler was being called even when the video was paused. The handler was also being called unnecessarily even after the video has completed and unmounted

* Saved and restored the state of the video during the activity state changed

* added progressUpdateInterval prop iOS

* add prop to Video.js

* added progressUpdateInterval prop iOS

* add prop to Video.js

Similar to #153, attempts to pause in fullscreen mode will be negated by the `playbackLikelyToKeepUp` event.

This PR adds a check for `_fullscreenPlayerPresented`, in additional to `_controls` before calling `setPaused` for `playbackLikelytoKeepUp`.

This update is likely preferrable to #258, as it doesn't lose the empty buffer check.

* Add Android Expansion File Support

* Added notes for usage with Android Expansion file

* Update README.md

Added notes re: expansion file usage.

* formatting issue fixes