Bring rust-jsonrpc into the rust-bitcoin organisation

[tcharding]

Do you still want to bring the rust-jsonrpc crate over to the rust-bitcoin organisation @apoelstra? If so, is there anything that needs doing before we can do so?

[apoelstra]

Yes -- and no, I don't think there's anything else. Does anyone have objections to this?

[Kixunil]

Feels a bit strange having a crate not directly related to Bitcoin here but not really an objection.

[apoelstra]

Its sole purpose is to talk to Bitcoin Core with less than 100 dependencies.