Update LiveTest to connect to either TestNet or MainNet.

Just getting my feet wet...
bitcoind actually has a regtest mode, which gives you full ability to create fake blocks, and really just do whatever you want. I think what we really probably want is to run against mainnet, but with the -regtest flag enabled so you aren't really at risk of losing money. I haven't played with it yet. This pr is fine though for now.

https://bitcoin.org/en/developer-examples#regtest-mode