Backup after each successful operation

[adammcarth]

Given the vulnerabilities of messing around with raw text files, I think it might be appropriate to backup each file after a successful operation is completed. That is, keep a working copy of the file so that if something goes wrong (during an update for instance), the file can be manually restored.

I like the idea of making these backups hidden files: blog_posts.json becomes .blog_posts.bak.