Many sparse changes
Moved user repository list to registry
Specify repository-states.json
Rework how we keep track of installed images.
Add setting for location of installed-images.json file.
Make location of subuser repositories user configurable.
Record the program sources from which images are built
Add executable-shortcut-installed flag in subusers.json
Remove depricated permissions
Remove system-dirs permission
program-source now image-source.  source-program now image-source
Add one more location for the repositories.json file.
Specify subuser image source URIs more exactly.
md files should not be executable