Add Money and Money Series (#505)

* Add Money class

* Standardize creation of money series

* Formatting

* Fix test

app/models/trend.rb

@@ -1,26 +1,27 @@
 class Trend
-    attr_reader :current, :previous
+  attr_reader :current, :previous, :type
 
-    def initialize(current, previous)
-        @current = current
-        @previous = previous
-    end
+  def initialize(current:, previous: nil, type: :asset)
+    @current = current
+    @previous = previous
+    @type = type # :asset means positive trend is good, :liability means negative trend is good
+  end
 
-    def direction
-        return "flat" unless @previous
-        return "up" if @current > @previous
-        return "down" if @current < @previous
-        "flat"
-    end
+  def direction
+    return "flat" unless @previous
+    return "up" if @current > @previous
+    return "down" if @current < @previous
+    "flat"
+  end
 
-    def amount
-      return 0 if @previous.nil?
-      @current - @previous
-    end
+  def amount
+    return 0 if @previous.nil?
+    @current - @previous
+  end
 
-    def percent
-      return 0 if @previous.nil?
-      return Float::INFINITY if @previous == 0
-      ((@current - @previous).abs / @previous.to_f * 100).round(1)
-    end
+  def percent
+    return 0 if @previous.nil?
+    return Float::INFINITY if @previous == 0
+    ((@current - @previous).abs / @previous.to_f * 100).round(1)
+  end
 end