_id of document: make this the content hash (IPFS address/ link)?

[phiweger]

This would allow us to link against those documents in a unified way, with all db participants using the same id for the same content.

This could then be naturally transferred to IPFS.

see:

• https://medium.com/ipdb-blog/a-decentralized-content-registry-for-the-decentralized-web-99cf1335291f
• https://github.com/ipld/specs
• https://github.com/ipld/specs/tree/master/ipld
• https://github.com/ipfs/faq/issues/98