Out-of-band blob storage

[jspahrsummers]

Storing large amounts of raw data in blocks directly may not be the most efficient solution, as these blocks will immediately get fanned out to all clients.

Potentially, it could make sense to build something like a distributed filesystem over the top, where large blobs can be placed for any client to access on-demand. The blobs should still be signed, and referenced in the blockchain using signed blocks, to limit cheating opportunities.