Asset packs checking thinks faceunits is a bad zip file

[joepal1976]

As per #387, the asset pack checking does not like the faceunits zip.

This stems down to the "packs/" dir not having a separate entry in the file (it lists "packs/faceunits01.json" directly without first mentioning the dir on a separate entry).

[joepal1976]

For people finding this now: You can safely choose "install anyway" on the faceunits01 asset pack. It's a valid pack, it's just erronously flagged as bad.

The fix will make it into MPFB 2.0.17.