Enhancement: Export/back up instance

[lungj]

I might try to tackle some MarkUs issues that I can reproduce on an existing MarkUs instance; it would be helpful if I could back up the entire instance (using a MarkUs admin account) and restore on a different machine. Of course, some user account renaming (or built-in account with no external authentication) needs to be used so that authentication can take place on the new machine,

[mishaschwartz]

resolved by #5069

• note that Rake task to archive/unarchive all stateful files from a MarkUs instance #5069 only archives/unarchives files on disk, you will also need to migrate the database manually to the new instance (if using postgres I would recommend the db_dump command)