Implement LastPrice for bitfinex.Client
Implement Balance for bitfinex.Client
Merge branch 'bitfinex'

Conflicts:
	src/bitcoin/bitfinex/client.go
gofmt
Stub implementation for bitfinex.Client.Fee always returnsing 0.12% since it doesn't seem to be available through the API.
Implement OpenOrders for bitfinex.Client
gofmt
Implement CancelOrder for bitfinex.Client
Implement Buy and Sell for bitfinex.Client