group controller refactoring

app/controllers/groups/application_controller.rb

+class Groups::ApplicationController < ApplicationController
+
+  private
+  
+  def authorize_admin_group!
+    unless can?(current_user, :manage_group, group)
+      return render_404
+    end
+  end
+end

app/controllers/groups/group_members_controller.rb

-class Groups::GroupMembersController < ApplicationController
+class Groups::GroupMembersController < Groups::ApplicationController
   before_filter :group
 
   # Authorize
@@ -37,12 +37,6 @@ class Groups::GroupMembersController < ApplicationController
     @group ||= Group.find_by(path: params[:group_id])
   end
 
-  def authorize_admin_group!
-    unless can?(current_user, :manage_group, group)
-      return render_404
-    end
-  end
-
   def member_params
     params.require(:group_member).permit(:access_level, :user_id)
   end

app/controllers/groups_controller.rb

-class GroupsController < ApplicationController
+class GroupsController < Groups::ApplicationController
   skip_before_filter :authenticate_user!, only: [:show, :issues, :members, :merge_requests]
   respond_to :html
   before_filter :group, except: [:new, :create]
@@ -132,12 +132,6 @@ class GroupsController < ApplicationController
     end
   end
 
-  def authorize_admin_group!
-    unless can?(current_user, :manage_group, group)
-      return render_404
-    end
-  end
-
   def set_title
     @title = 'New Group'
   end