AppImage download fallback for Appi

Caramel reported Appi, the AppImage package manager, failing to download Calibre:

https://forum.puppylinux.com/viewtopic.php?p=165616#p165616

There used to be a fallback folder on ibiblio.org, but it got removed when I had a big cleanout of the easyos ibiblio files. Have now restored the download fallback, here:

https://distro.ibiblio.org/easyos/amd64/packages/appimage/easyos/devuan/excalibur/

This has required fixes in /usr/local/appi/appi script, which will be in the next release of EasyOS.    

Tags: easy