BitVc/Huobi Implementation

Provides an implementation of the trading API of BitVC (bitvc.com), and market data API for Huobi. BitVC executes trades on Huobi, and they suggest getting market data straight from Huobi. 

Two comments:
- Borrowed money is shown in a separate wallet, the main wallet contains the sum of all existing wallets (borrowed + frozen)
- Trade history is currently not supported unfortunately. If anyone has an idea how to do that, please commit.

This is mostly based on @sutra client code. Thanks!