Fixed getFee() for binance exchange

[olexiyb]

• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  Bug fix

• What is the current behavior? (You can also link to an open issue here)
  binance.getFee() - 0.1
  bitfinex.getFee() - 0.002

• What is the new behavior (if this is a feature change)?
  binance.getFee() - 0.001
  bitfinex.getFee() - 0.002

• Other information:
  Here is binance raw response. As you can see binance gives us fee as 10, when I would expect 0.1
  { makerCommission: 10,
  takerCommission: 10,
  buyerCommission: 0,
  sellerCommission: 0,
  canTrade: true,
  canWithdraw: true,
  canDeposit: true,

So we need to divide by 10000 to get decimal fee for binance

[olexiyb]

@askmike BTW why gekko does not use?

https://www.npmjs.com/package/ccxt

this library looks like implements interface to all exchanges

[askmike]

nice catch, thanks!

[askmike]

this library looks like implements interface to all exchanges

It's a huge library and doesn't play nice with Gekko Broker (Gekko's internal order execution library).