Display error message in web UI when event source disconnects
Show start and end time for current show
Display progress bar until end of show
Set mono audio output for radiodan server
Emit 'exit' event and transition to standby when app terminates

All connected web clients will show the correct UI state
and will display a helpful error.
Move exit state action into gracefulExit handler
Bind HTTP API to shutdown and restart actions
Display shutdown messages in web UI
Physical UI now uses shutdown state action
Merge pull request #11 from radiodan/transition-to-standby-on-exit

Emit 'exit' event and transition to standby when app terminates
Display next programme in web ui
Change web UI to match event stream message structure
parse int to base 10
Emit service events over Event Stream

- Simplify event types emitted by service instances
- Send over Event Stream
Fix crash when starting with my-music selected
Remove station info from nowAndNext message
Refine messages sent through event stream

- Event Bus now uses EventEmitter2
- Opt-in to specific messages sent through stream
Add SETTINGS_PATH environment variable.

So that settings files can persist between deployments, allow the path to be set by the user.