create draft state flag

most course objects will be getting draft state implementations
soon, but we don't want to show publishing stuff until it's
implemented everywhere.

Test Plan:
 * N/A

closes #CNVS-5280

Change-Id: Ie5500b35f9e912d8ae6b5845ce0a238fb9a72927
Reviewed-on: https://gerrit.instructure.com/19589
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Zach Pendleton <zachp@instructure.com>
Product-Review: Bracken Mosbacker <bracken@instructure.com>
QA-Review: Bracken Mosbacker <bracken@instructure.com>

app/controllers/context_modules_controller.rb

@@ -85,7 +85,11 @@ class ContextModulesController < ApplicationController
   def create
     if authorized_action(@context.context_modules.new, @current_user, :create)
       @module = @context.context_modules.build
-      @module.workflow_state = 'active'
+      if @domain_root_account.enable_draft?
+        @module.workflow_state = 'unpublished'
+      else
+        @module.workflow_state = 'active'
+      end
       @module.attributes = params[:context_module]
       respond_to do |format|
         if @module.save

app/models/account.rb

@@ -150,6 +150,7 @@ class Account < ActiveRecord::Base
   add_setting :users_can_edit_name, :boolean => true, :root_only => true
   add_setting :open_registration, :boolean => true, :root_only => true
   add_setting :enable_scheduler, :boolean => true, :root_only => true, :default => false
+  add_setting :enable_draft, :boolean => true, :root_only => true, :default => false
   add_setting :calendar2_only, :boolean => true, :root_only => true, :default => false
   add_setting :show_scheduler, :boolean => true, :root_only => true, :default => false
   add_setting :enable_profiles, :boolean => true, :root_only => true, :default => false