Implement action types pause, resume and restart

[Orbiter]

Describe the solution you'd like
If a media file is played, it is possible to say "stop" to stop playing. Similarly, with the following action types, it should be possible to

• pause the playing of a media file (youtube, mp3 etc) with the action type pause
• resume the playing of a media file which has been paused with the action type resume
• restart the playing of a media file (either currently playing or paused) with the action type restart

Additional context
Examples:
https://api.susi.ai/susi/chat.json?q=pause

"actions": [{"type": "pause"}]

https://api.susi.ai/susi/chat.json?q=resume

"actions": [{"type": "resume"}]

https://api.susi.ai/susi/chat.json?q=restart

"actions": [{"type": "restart"}]

[jogendra]

@Orbiter Currently, youtube video etc is playing over chat screen so the user can't use these actions without closing youtube player. If we play video/MP3 within app then there will be multiple instances of Player, which is not a good practice.