Bittrex getCandles support

[talvasconcelos]

Hi, would you care about adding getCandles, buy and sell endpoints available for the Bittrex v2.0 API?

Best regards,
Tiago

[passabilities]

This will definitely be on the todo list, but since not every exchange offers this data you could just use the internal Bittrex npm package that includes this endpoint.

NOTE: that because the package reference isn't created until the constructor is called, you will have to do this:

let CE = require('crypto-exchange')
let bittrex = new CE.bittrex
bittrex.getcandles({
  marketName: 'USDT-BTC',
  tickInterval: 'fiveMin', // intervals are keywords
}, function( data, err ) {
  console.log( data );
})