setSpeed not working in IE11 and Safari11

[alextrastero]

First of all thanks for the work on this library, it's 💯

We got an issue with setSpeed where if we set it before the play() it will not work in Safari and IE11, if we edit dist/buzz.js and use defaultPlaybackRate instead of playbackRate it does though.

// We've changed:
buzzSound.setSpeed(playbackRate);

// to:
buzzSound.sound.playbackRate = playbackRate; // makes it work in Chrome & Firefox
buzzSound.sound.defaultPlaybackRate = playbackRate; // makes it work in Safari and IE11

Anyone else run into this issue?