create pseudonym registration done notification

fixes CNVS-31821

test plan
- run migrations
- ensure that pseudonym done notification is sent when creating
 a user as an admin via the api with these parameters:
user[skip_registration]=true
pseudonym[send_confirmation]=true
communication_channel[skip_confirmation]=false

Change-Id: Idd3a48afb8364ff49605e59080c324c459307444
Reviewed-on: https://gerrit.instructure.com/91617
Tested-by: Jenkins
Reviewed-by: James Williams  <jamesw@instructure.com>
QA-Review: Heath Hales <hhales@instructure.com>
Product-Review: Joel Hough <joel@instructure.com>

db/migrate/20160929151753_create_pseudonym_registration_done_notification.rb

@@ -0,0 +1,17 @@
+class CreatePseudonymRegistrationDoneNotification < ActiveRecord::Migration
+  tag :predeploy
+
+  def self.up
+    return unless Shard.current == Shard.default
+    Canvas::MessageHelper.create_notification({
+                                                name: 'Pseudonym Registration Done',
+                                                delay_for: 0,
+                                                category: 'Registration'
+                                              })
+  end
+
+  def self.down
+    return unless Shard.current == Shard.default
+    Notification.where(name: 'Pseudonym Registration Done').delete_all
+  end
+end