Stream audio to mobile device

## Problem

I have always wanted to watch something on my computer with my larger monitors and listen from afar via my mobile device (iOS devices: iPhone, iPad). It looks like [Airfoil](http://www.rogueamoeba.com/airfoil/mac/) is the solution, _however_ there is an audio delay and for video content this can ruin the experience.
## Solution: Playback + Mobile companion app

Now that we have Playback, we can create a proper solution. It would allow for us to stream audio content ahead of the video and allow the mobile device to buffer and sync up with the video stream! While something like Airfoil has to receive the audio and process it immediately, Playback knows what audio is coming next and can buffer this on the mobile device ahead of time.
### Implementation: Mobile companion app

The mobile app could be implemented in a web app and Playback would simply start an Express server that would serve the audio to buffer. By making it a simple web app we could have more support for devices (not just iOS, etc).

This all, of course, is easier said than done. I think this is something that Playback could achieve, and it is within scope of Playback and Playback has a very unique opportunity to solve this problem. However, I may be the only user with such a scenario.

Please let me know what you think! Including potential recommendations for implementation. I would love to contribute and help submit a pull request for this feature!
Thank you! :smiley:

No files, tests, or entry points are named. Start by surveying Playback's existing Electron and Node.js architecture and evaluating the proposed companion web app, buffering, and synchronization against the current scope; done would require agreed requirements and an implementation plan.

Written by the indexing model from the issue text.