Add AppImages from AppImageHub.com

[UriHerrera]

Currently, the front-end lists the AppImage files from https://appimage.github.io/ only, adding the AppImages also hosted in http://www.appimagehub.com/ would add more content that is available to users, if there are files that exist in both sites only list one of the AppImages in the front-end.

[cadamsdev]

@UriHerrera Do you happen to know if there's an api available?

e.g one similar to this
https://appimage.github.io/feed.json

[UriHerrera]

According to their site

OCS-API

https://www.freedesktop.org/wiki/Specifications/open-collaboration-services/
https://en.wikipedia.org/wiki/Open_Collaboration_Services

OCS-API in use

ocs-url: https://www.opendesktop.org/p/1136805/
KDE Attica Library: https://techbase.kde.org/Development/Tutorials/Collaboration/Attica/Introduction
KDE KNewStuff Frontend: https://techbase.kde.org/Development/Tutorials/Collaboration/HotNewStuff