Stop and restart audio if already playing

Prevent double audio when using Double Check

Add and remove the listener on the didFinalAnswer event to avoid the double invocation

Move the listener setup to the end of the promise chain

Update version

Add options to the didFinalAnswer listener too

Made the bell pause -> play statements less confusing

Merge pull request #19 from bashenk/patch-burn-bell-audio

Patch Burn Bell audio, closes #15

switch audio to base64 encoded string instead of remote url