Coinmarketcap implementation (#243)

* Updates requester package to allow unpacking of zipped files and defaults to warn if no JSON is present

* Initial addition of coinmarketcap functionality

* fix requested changes

* Fix issue with displaying false positive in request.go && reorder plan list

* Rename CurrencyProvider -> CryptocurrencyProvider
Skip seeding currency data if not enabled
Rm line in main.go

* Update test procedures and relevant json files

* Fix const issue within config.go

testdata/configtest.json

@@ -48,6 +48,13 @@
     "primaryProvider": false
    }
   ],
+  "cryptocurrencyProvider": {
+   "name": "CoinMarketCap",
+   "enabled": false,
+   "verbose": false,
+   "apiKey": "Key",
+   "accountPlan": "accountPlan"
+  },
   "cryptocurrencies": "BTC,LTC,ETH,DOGE,DASH,XRP,XMR",
   "currencyPairFormat": {
    "uppercase": true,