This change adds the ability to prove and check a reserve proof
to this existing "Prove/check" advanced menu. If the amount line has
a valid amount less than that of the current account index this input
will drive the logic for generating a reserve proof. Checking a reserve
proof is accomplished by validating the address and verifying that
signature.indexOf("ReserveProofV") === 0. The result displays the total
and spent amount of the proof.