Use bitswap to retrieve params directly from IPFS

[iand]

Rather than centralizing access through a gateway, use bitswap to read the files from ipfs peers.

[aschmahmann]

As an aside it would also be really snazzy if once markets processes have the ability to serve content over Bitswap if SPs could be set up to serve params that way. This would allow SPs to swarm download the proofs from each other pretty quickly as it moves out to all of the nodes on the network.

[jennijuju]

Thanks for creating the issue!