#117 Add a backup computer feature

[J. Scott Edwards]

Create a new backup feature where instead of backing up all of the files that were part of the GNU/Linux distribution it just stores the id of that public file, that way it only has to store the data for the files that are unique to that computer. Could also have public directory trees for the distribution (for example: /usr) so you wouldn't have to store the entire tree just the id of that tree. This could also be used to verify that there were not any unknown files on your machine.