Account namespace updates: part 5 (valuations) (#901)

* Move Valuation to Account namespace

* Move account history to controller

* Clean up valuation controller and views

* Translations and cleanup

* Remove unused scopes and methods

* Pass brakeman

app/models/account.rb

@@ -29,6 +29,10 @@ class Account < ApplicationRecord
     balances.where("date <= ?", date).order(date: :desc).first&.balance
   end
 
+  def favorable_direction
+    classification == "asset" ? "up" : "down"
+  end
+
   # e.g. Wise, Revolut accounts that have transactions in multiple currencies
   def multi_currency?
     currencies = [ valuations.pluck(:currency), transactions.pluck(:currency) ].flatten.uniq