Admin base controller (#1465)

* Add Admin::BaseController to wrap admin area

Extracts the setting of the `admin` layout and verifying that users are admins
to a common base class for the admin/ controllers.

* Add basic coverage for admin/reports and admin/settings controllers

app/controllers/admin/settings_controller.rb

@@ -1,35 +1,33 @@
 # frozen_string_literal: true
 
-class Admin::SettingsController < ApplicationController
-  before_action :require_admin!
-
-  layout 'admin'
-
-  def index
-    @settings = Setting.all_as_records
-  end
-
-  def update
-    @setting = Setting.where(var: params[:id]).first_or_initialize(var: params[:id])
-    value    = settings_params[:value]
-
-    # Special cases
-    value = value == 'true' if @setting.var == 'open_registrations'
-
-    if @setting.value != value
-      @setting.value = value
-      @setting.save
+module Admin
+  class SettingsController < BaseController
+    def index
+      @settings = Setting.all_as_records
     end
 
-    respond_to do |format|
-      format.html { redirect_to admin_settings_path }
-      format.json { respond_with_bip(@setting) }
+    def update
+      @setting = Setting.where(var: params[:id]).first_or_initialize(var: params[:id])
+      value    = settings_params[:value]
+
+      # Special cases
+      value = value == 'true' if @setting.var == 'open_registrations'
+
+      if @setting.value != value
+        @setting.value = value
+        @setting.save
+      end
+
+      respond_to do |format|
+        format.html { redirect_to admin_settings_path }
+        format.json { respond_with_bip(@setting) }
+      end
     end
-  end
 
-  private
+    private
 
-  def settings_params
-    params.require(:setting).permit(:value)
+    def settings_params
+      params.require(:setting).permit(:value)
+    end
   end
 end