Closes: #2.
Libp2p supports multiple cryptographic curves, however we have currently only implented support for secp256k1.
This needs to be run with the compiler flag `libp2p_pki_schemes` set to `secp256k1`. If running the tests, this can be run like so: `nimble test —libp2p_pki_schemes=secp256k1` to put secp as the first supported crypto scheme.
Swap all instances of Record with SignedPeerRecord.
Allow for `SignedPeerRecord`s to be updated by updating the first multiaddress in the `PeerRecord`. This also increments the `seqNo` in the `PeerRecord` only if the address was actually updated.