Add Money and Money Series (#505)

* Add Money class

* Standardize creation of money series

* Formatting

* Fix test

app/models/money.rb

@@ -0,0 +1,32 @@
+class Money
+    attr_reader :amount, :currency
+
+    def self.from_amount(amount, currency = "USD")
+        Money.new(amount, currency)
+    end
+
+    def initialize(amount, currency = :USD)
+        @amount = amount
+        @currency = currency
+    end
+
+    def cents(precision: nil)
+        _precision = precision || CURRENCY_OPTIONS[@currency.to_sym][:precision]
+        return "" unless _precision.positive?
+
+        fractional_part = @amount.to_s.split(".")[1] || ""
+        fractional_part = fractional_part[0, _precision].ljust(_precision, "0")
+    end
+
+    def symbol
+        CURRENCY_OPTIONS[@currency.to_sym][:symbol]
+    end
+
+    def separator
+        CURRENCY_OPTIONS[@currency.to_sym][:separator]
+    end
+
+    def precision
+        CURRENCY_OPTIONS[@currency.to_sym][:precision]
+    end
+end