Add play function to Kino.Audio

[relardev]

I was looking for a way to notify myself when some event happens, tried implementing Kino.JS.Live that sends browser notification but didn't managed to make it work. Ended up using Kino.Audio with added functionality for playing the audio from the code:

      kino = Kino.Audio.new(...)
      // somewhere else, when some event happens
      Kino.Audio.play(kino)

I can open a PR if there is interest in adding this to Kino

[jonatanklosko]

Sounds good, a PR is welcome :) In that case it would make sense to pair it with Kino.Audio.pause/1.

[jonatanklosko]

Closed in #458.