Audio task

exploratory task for mp3 -> mp4 conversion task.

This pulls and mp3 down from our S3 uploads bucket, runs the ffmpeg command that Jon specified on it, and uploads the result to the CUIT server.

Currently, this is set up as a manual operation, completely out of the normal path, so it should not affect existing uploads. This is just to get it in place so we can test it and verify that it works as desired.

Once that happens, we'll change it to replace the PCP/ET step and probably make it just work off the original uploaded file that's sitting in WC's temp directory instead of pulling down from S3.