Add walletFx and fix explorer

Add walletFX key to currencie object and fix explorer as it is an array 
instead than a string

Author: ezewer

lib/currency.js

@@ -2,6 +2,7 @@
 
 const numberValidator = require('./validators/number')
 const stringValidator = require('./validators/string')
+const arrayValidator = require('./validators/array')
 const currencyValidator = require('./validators/currency')
 const Model = require('./model')
 
@@ -10,7 +11,8 @@ const fields = {
   name: 1,
   pool: 2,
   explorer: 3,
-  symbol: 4
+  symbol: 4,
+  walletFx: 5
 }
 
 /**
@@ -52,8 +54,9 @@ class Currency extends Model {
         id: numberValidator,
         name: stringValidator,
         pool: stringValidator,
-        explorer: stringValidator,
-        currency: currencyValidator
+        explorer: arrayValidator,
+        currency: currencyValidator,
+        walletFx: arrayValidator
       }
     })
   }