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/valuation.rb

@@ -1,13 +0,0 @@
-class Valuation < ApplicationRecord
-  include Monetizable
-
-  belongs_to :account
-  validates :account, :date, :value, presence: true
-  monetize :value
-
-  scope :in_period, ->(period) { period.date_range.nil? ? all : where(date: period.date_range) }
-
-  def self.to_series
-    TimeSeries.from_collection all, :value_money
-  end
-end