postTX should have options to view Faeth metadata

A Faeth transaction includes a few pieces of metadata:

- The required recipient address
- The required Ether value sent to that address
- The Ethereum portion of the input (intended as the argument to an ABI-compliant contract call)
- The signers, both present and required, of the Fae transaction.

All of these should be exposed through postTX options, as they are all necessary data for a potential Ethereum user to act upon.