Merge pull request #602 from shakyink/feature/cryptoexchange_api

Added more crypto currency exchanges including nexchange and poloniex

README.md

@@ -161,6 +161,8 @@ API | Description | Auth | HTTPS | CORS | Link |
 | 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) |
 | 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/) |
+| Poloniex | US based digital asset exchange | `apiKey` | Yes | Unknown | [Go!](https://poloniex.com/support/api/) |
 
 ### Currency Exchange
 API | Description | Auth | HTTPS | CORS | Link |