391 Notification refactorings (#441)

* Refactor notifications to allow easier plugins

* Notification refactoring

* Formatting

* Move news to NewsService; cleanup of events

* More refactoring; added send email out for news item and the template

* Formatting

* Formatting

config/notifications.php

@@ -0,0 +1,26 @@
+<?php
+
+use App\Notifications\Messages\AdminUserRegistered;
+use App\Notifications\Messages\NewsAdded;
+use App\Notifications\Messages\PirepAccepted;
+use App\Notifications\Messages\PirepRejected;
+use App\Notifications\Messages\PirepSubmitted;
+use App\Notifications\Messages\UserPending;
+use App\Notifications\Messages\UserRegistered;
+use App\Notifications\Messages\UserRejected;
+
+return [
+    /*
+     * The channels that notifications are sent on
+     */
+    'channels' => [
+        AdminUserRegistered::class => ['mail'],
+        NewsAdded::class           => ['mail'],
+        PirepAccepted::class       => ['mail'],
+        PirepRejected::class       => ['mail'],
+        PirepSubmitted::class      => ['mail'],
+        UserPending::class         => ['mail'],
+        UserRegistered::class      => ['mail'],
+        UserRejected::class        => ['mail'],
+    ],
+];