Remove leftover sandbox code

The rest of the sandbox code was removed in commit d679c1eb.

app/controllers/sandbox_controller.rb

@@ -1,45 +0,0 @@
-class SandboxController < ApplicationController
-  skip_authorization_check
-
-  layout :set_layout
-
-  helper_method(:namespace)
-
-  def index
-    @templates = Dir.glob(Rails.root.join("app", "views", "sandbox", "*.html.erb").to_s).map do |filename|
-      filename = File.basename(filename, File.extname(filename))
-      filename unless filename.starts_with?("_") || filename == "index.html"
-    end.compact
-  end
-
-  def show
-    if params[:template].index(".") # CVE-2014-0130
-      render action: "index"
-    elsif lookup_context.exists?("sandbox/#{params[:template]}")
-      if params[:template] == "index"
-        render action: "index"
-      else
-        render "sandbox/#{params[:template]}"
-      end
-
-    elsif lookup_context.exists?("sandbox/#{params[:template]}/index")
-      render "sandbox/#{params[:template]}/index"
-    else
-      render action: "index"
-    end
-  end
-
-  private
-
-    def set_layout
-      if params[:template] && params[:template].split("_").first == "admin"
-        "admin"
-      else
-        "application"
-      end
-    end
-
-    def namespace
-      "admin"
-    end
-end

config/routes.rb

@@ -1,12 +1,6 @@
 Rails.application.routes.draw do
 
   mount Ckeditor::Engine => "/ckeditor"
-
-  if Rails.env.development? || Rails.env.staging?
-    get "/sandbox" => "sandbox#index"
-    get "/sandbox/*template" => "sandbox#show"
-  end
-
   mount LetterOpenerWeb::Engine, at: "/letter_opener" if Rails.env.development?
 
   draw :account