Replace audio-encoder dependency

[igorski]

Versions above 1.0.2 have an error Uncaught (in promise) ReferenceError: MPEGMode is not defined, which stems from an outdated lamejs dependency.

The Git repository for lamejs is updated, but the NPM module isn't, which is why package.json includes the "lamejs": "github:zhuker/lamejs" dependency. Also see zhuker/lamejs#89

This is less than ideal. If the lamejs-library isn't published, or audio-encoder isn't updated to use a different library, we should find a suitable replacement.