Replace GDAX with Coinbase Pro (#740)

GDAX is being replaced/rebranded as Coinbase Pro

README.md

@@ -169,13 +169,13 @@ API | Description | Auth | HTTPS | CORS | Link |
 | Blockchain | Bitcoin Payment, Wallet & Transaction Data | No | Yes | Unknown | [Go!](https://www.blockchain.info/api) |
 | CoinAPI | All Currency Exchanges integrate under a single api | `apiKey` | Yes | No | [Go!](https://docs.coinapi.io/) |
 | Coinbase | Bitcoin, Bitcoin Cash, Litecoin, and Ethereum Prices | `apiKey` | Yes | Unknown | [Go!](https://developers.coinbase.com) |
+| Coinbase Pro | Cryptocurrency Trading Platform | `apiKey` | Yes | Unknown | [Go!](https://docs.pro.coinbase.com/#api) |
 | CoinBin | Cryptocurrency information | No | Yes | Unknown | [Go!](https://coinbin.org/) |
 | CoinDesk | Bitcoin Price Index | No | No | Unknown | [Go!](http://www.coindesk.com/api/) |
 | Coinigy | Interacting with Coinigy Accounts and Exchange Directly | `apiKey` | Yes | Unknown | [Go!](https://coinigy.docs.apiary.io) |
 | CoinMarketCap | Cryptocurrencies Prices | No | Yes | Unknown | [Go!](https://coinmarketcap.com/api/) |
 | CryptoCompare | Cryptocurrencies Comparison | No | Yes | Unknown | [Go!](https://www.cryptocompare.com/api#) |
 | Cryptonator | Cryptocurrencies Exchange Rates | No | Yes | Unknown | [Go!](https://www.cryptonator.com/api/) |
-| GDAX | Cryptocurrency Trading Platform | `apiKey` | Yes | Unknown | [Go!](https://docs.gdax.com/#api) |
 | Livecoin | Cryptocurrency Exchange | No | Yes | Unknown | [Go!](https://www.livecoin.net/api) |
 | MercadoBitcoin | Brazilian Cryptocurrency Information | No | Yes | Unknown | [Go!](https://www.mercadobitcoin.net/api-doc/) |
 | Nexchange | Automated cryptocurrency exchange service | No | No | Yes | [Go!](https://nexchange2.docs.apiary.io/) |