fix(revaultd/client): use crate jsonrpc instead

[edouardparis]

https://github.com/apoelstra/rust-jsonrpc/ or async-jsonrpc

[darosior]

The rust-jsonrpc crate can now be added support for UDS transport, which i believe would be welcome. Maybe post an issue there to ask them or ask on #rust-bitcoin on freenode.

[darosior]

Update on this issue: rust-jsonrpc is going to support UDS soon. See #147 as a dirty PoC.