hmm. storj and maidsafe might do it. although what i was thinking was a little different. pretty sure some of the other ones are just using blockchain as a buzzword
edit: it would seem like a few of the projects listed on that github are dead or super early alpha
That is possible....I just searched google "blockchain storage documents" then a lot of them appear.
It just shows that there is a lot available....
http://www.acronis.com/en-us/business/blockchain-notary/