add admin user interface

app/controllers/admin/users_controller.rb

@@ -0,0 +1,16 @@
+module Admin
+  class UsersController < ApplicationController
+    before_filter :admin_only
+    
+    def edit
+      @user = User.find(params[:id])
+    end
+    
+    def update
+      @user = User.find(params[:id])
+      @user.level = params[:user][:level]
+      @user.save
+      redirect_to admin_user_path(@user, :notice => "User updated")
+    end
+  end
+end