Update LiveTest to connect to either TestNet or MainNet.

Just getting my feet wet...
Sorry, circling back to this.

I think it'll be best to just pick one -- probably regtest. Tbh it doesn't matter right now, since I'm only at the point of testing basic connection and version message exchange, so I think I'm just going to leave it using mainnet for now until there is a need to decide.

If you want a good chunk of work to get your feet wet, a lot of the message commands are still undefined in Message.Command :)

I also have a TODO to use hmac-drbg for key derivation in the ECKey class. That is currently the industry best practice. Aaron Voisine has an implementation here for breadwallet:
https://github.com/voisine/breadwallet/blob/master/BreadWallet/BRKey.m#L35