Use Notification/Notifiable (#379)

* Add migrations for notifiables

* Configure spatie-backup to run as part of cron

* Convert Mailer to Notification; add pirep notifications

* Styling

resources/views/mail/user/pending.blade.php

@@ -0,0 +1,8 @@
+@component('mail::message')
+# Thanks for signing up, {{ $user->name }}!
+
+You will be notified as soon as your account is approved!
+
+Thanks,<br>
+Management, {{ config('app.name') }}
+@endcomponent