More preparation for the Appstore.

Added the ability to Install/Upgrade/Uninstall/Start/Stop an appstore application
Added counter of how many updates is available.
Added "Store" level for applications (The AppStore can contain many "Stores")
Added Installed application Icons (they are unpacked to "appImages" folder under the administrator "scadmin".
Removed unused files

When uninstalling an AppStore app the image is now also removed
Added error code return for LoadDependencies.
Merge branch 'develop' of https://github.com/Starcounter/Starcounter into develop