New Settings Menu, Routes and Controllers Organization (#641)

* Add new settings routes and controllers

* Add new settings view, restructure controllers and routes

* Fix lint errors

app/controllers/transactions/categories_controller.rb

@@ -1,6 +1,9 @@
 class Transactions::CategoriesController < ApplicationController
   before_action :set_category, only: [ :update, :destroy ]
 
+  def index
+  end
+
   def create
     if Current.family.transaction_categories.create(category_params)
       redirect_to transactions_path, notice: t(".success")

app/controllers/transactions/merchants_controller.rb

@@ -0,0 +1,4 @@
+class Transactions::MerchantsController < ApplicationController
+  def index
+  end
+end

app/controllers/transactions/rules_controller.rb

@@ -0,0 +1,4 @@
+class Transactions::RulesController < ApplicationController
+  def index
+  end
+end