Remove dead code in player.haml.
Implement volume (read-only for now).
Allow floats to be passed into payloads.
Implement setting volume.
Tidy up the playlist request handlers.
Allow access to update channel from views.
Start using OpenStruct for responses.

This allows less coupling to Hash for items using responses.

Uses of values_at on responses are being removed.
Explicitly check websocket status before sending.
Remove extraneous .run.
Use OpenStruct methods where possible.