Need to know the source, disable editing details for other people's files

@grote Currently in repomaker, you can edit the details for anything you add to your repo, even if you are not the creator of the file. This has the potential to create a lot of unwanted problems.

I believe we need a way to know if you are the source/creator of a file, and only allow you to edit those files which you upload. If someone adds apps from the Guardian Project's repo, they shouldn't be able to change the app info.

One idea—require users to login if they want to add original content (i.e. upload files). When they upload files, we allow permission to edit them. If they are adding files from other repos, do not allow them to edit.