Polyfill getUserMedia etc. so that plugin can be used seamlessly on all platforms

[edin]

I believe that most users of this plugin, use it as a 1-1 substitute for getUserMedia, since it still isn't available in the iOS WebViews. It would be tasteful to be able to hide the custom API of this plugin behind a polyfill for getUserMedia. On platforms where getUserMedia exists, it would be returned instead, while on iOS the plugin is used to power the same thing.

This would require implementing parts of:

• navigator.mediaDevices.getUserMedia
• MediaStreamConstraints
• MediaStream
• MediaStreamTrack
• MediaDevices for example enumerateDevices() should be possible to use.

Including the events associated with the above.