Support Coinbase #48
Description
Please, support Coinbase again. Even though it was phased out here in the past, in 2017 and 2018 this is a viable exchange. See also https://en.wikipedia.org/wiki/Coinbase
Old support can be found at https://github.com/drpout/libdynticker/blob/620bd414a0913518c44257d7a327debab37e8ebe/src/test/java/mobi/boilr/libdynticker/exchanges/CoinbaseExchangeTest.java
API documentation for v2 and v1 can be found at https://developers.coinbase.com/ and for GDAX see https://developers.coinbase.com/docs/exchange/