So apparently there is already someone who have made the paf file required to install Atom.io in portable mode here: http://sourceforge.net/projects/atomportable/
I would just really love to see it in my update catalog, so I don't have to manually update it.
Program: Atom
License: Open Source/MIT
Description: Very compact multi language IDE.
Website: http://atom.io/
Other: There is already built a PortableApps package for it.
In the future, please search first: https://portableapps.com/node/53227