Adding support for EasyAudioEncoder (EAE) audio transcoding

[pabloromeo]

Adding support for EAE.
The new default is for it to be enabled but if issues occur it can be turned off by setting the environment variable EAE_SUPPORT in the Workers to "false"

Solves #125 and #155

[pabloromeo]

@ValZapod, it probably is simpler. However, patching their binary and skipping their licencing most likely breaks their TOS, same with re-distributing their binary separately.
Also, it would be yet another thing to maintain when Plex makes changes to it. By mimicking what Plex already does now the chances are higher for it to be compatible with their next release without making changes each time. The same applies to their other codecs, we download them just as any Plex instance does. But you are right, it is more cumbersome and complex and harder to extend, since Plex isn't open-source and it implies a ton of trial and error.