As an organizer, I want to be informed when the Invitation List is ready, so that I can view and then make decisions about who to invite to my event.

Acceptance Criteria:

• Given than an Invitation List has been generated for an organizer,
  • They should receive a web notification that their invitation list is ready, which reads: "Your Invitation List is ready."
  • The words "Invitation List" should link to the appropriate Invitation Lust
• The default should be web notification but organizer should be able to also turn on email notification in Preferences (Preferences > Notifications > Notify me about these events)
• The notification should be called "Invitation list generated"