Crop icon/image vandalism prevention

A concern we have at FarmBot is someone deleting all the crop icons we've uploaded and/or uploading something inappropriate and that then being served to our users (and eventually on OpenFarm itself).

What are some options for preventing this type of vandalism? Here are some ideas off the top of my head:

• Limit image/icon management to admins/trusted people (tight control, but less contributions)
• Only allow an original uploader/admins to remove the things they've uploaded (prevents mass deletion but not inappropriate uploads)
• Have a moderation mechanism whereby admins/moderators need to approve changes (tight control, potentially lots of work for mods, potentially deters contributions because their changes aren't live) Could be combined with:
• Users can get more abilities the more they use the site (doesn't necessarily prevent vandalism, limits contributions from new users)
• Have database history so admins can reverse vandalism when they spot it or when its flagged (reactive, not proactive)
• Allow icons to be tagged so that icons "sets" can be made. Only icons with the right tag would be pulled into the 3rd party app. For example, the FarmBot web app would only pull in icons tagged "FarmBot". This would allow style to be preserved in 3rd party apps while allowing multiple icon styles to be uploaded. Users would need to be granted the ability to apply certain tags. For example, only I would be allowed to add the FarmBot tag. (complicated)

When there's no icon yet (i.e. we're using the default), we should allow uploading icons.

However, when one already exists, how about users can only propose replacements, and moderators need to approve them.

I think that's a good first step in preventing vandalism. Might require a decent amount of work to implement though?