Created a script find 'createdat' fields in documents and copy the value...

... into a 'createdAt' field for the same document.

Making sure every document has a 'createdAt' field ( and not just a 'createdat' which was caused by a typobug earlier ) will help with sorting. This doesn't yet cover those document with neither 'createdat' or 'createdAt', there we have to agree on what to do, remove them if they're not needed, or just set a old datetime to make sure they end up back in history where they belong. 

works on my local, but we shouldn't risk losing or destroying data before testing a bit more.