Add Coinbase

Author: amacneil

composer.json

@@ -10,6 +10,7 @@
         "authorize.net",
         "buckaroo",
         "cardsave",
+        "coinbase",
         "commweb",
         "dps",
         "egate",
@@ -61,6 +62,7 @@
         "omnipay/authorizenet": "~2.0",
         "omnipay/buckaroo": "~2.0",
         "omnipay/cardsave": "~2.0",
+        "omnipay/coinbase": "~2.0",
         "omnipay/common": "~2.1.0",
         "omnipay/dummy": "~2.0",
         "omnipay/eway": "~2.0",