Custom lightwalletd back-end/Socks proxy client/Tor client support

[warelock2]

These are enhancement requests:

1. Please add the ability to point the Skull Island to a custom lightwalletd service, such as my own. My lightwalletd instance is backed by my own Treasure Chest full node instance.

2. Please also add a socks proxy feature, so I can point Skull Island to my lightwalletd instance over Tor, using the Orbot Android app. Either that or embed a tor client in Skull Island. Thanks

[satindergrewal]

Agree to this request.

I also added this request for PirateWallet-Lite client for Desktop and command line here:

PirateNetwork/PirateWallet-Lite#141