Standardizing App format

I write this because I want to express my two cents on app format.
I think we should support only ONE type of application format (excluding spare executables files).
I read in https://github.com/helloSystem/hello/wiki/Architecture that there are 3 suggestions of which format we could use. But I think that it would a better idea to not rely on nothing else than AppImage.

Here are my points:
1) AppImage is a well-known and reliable distro-agnostic app packaging system. This means that apps are already bundled this way by more and more developers. No need to reinvent the weel another time, even if following GNUstep idea.

2) We should reduce terminal usage, and so repository and ppa needings. Mere Mortals definitely don't want them. To achieve this, we should even not include a standard package manager (aka pgk, apt, pacman, etc). Everything sould be accessible by "googling" and standard FTP download & Drag'n'Drop in Applications folder.

3) AppImages can be easily brought to other non-Hello systems even if they don't support GNUstep-like or ROX-style type of app packing. This shoudn't be possible by "inventing" another non-common and unsupported style of app allocation. AppImage is well known and shared in major Unix-like distros nowadays. Maybe we could include both Linux and BSD types of executables, so Linux users should not use Alien utility.

4) Using ".app" folders could confuse unaware Mac users.

5) If a non-AppImage .pkg is dragged into Applications folder, we should configure a dipendency-discovery system (such as dpkg) to download them an then we should repack the app in a working AppImage, wich is still bringable to other systems without any other effort. No single terminal line needed for that, this should "Just work".

**Notes:**
- While reaching point (2) is only doable in the long term, we could automatically ensure compatibility with AppImages compiled for Linux. That's doable by using Alien conversion tool and auto-configure it for this very purpose.

- We can make AppImages explorable by file browser by adding an "Explore Package content" option on the right click, just like Macs.

- Just in case someone has to operate with AppImages via terminal, I suggest to use a smaller name for that apps, without capitalization. For this purpuse, I suggest something like `.appkg` extention, with is shorter, simple to undertsand, remember and without any capitalization.

Hope I'm not a fool :D.
-Cyano