Added commands to delete component group (also fixes bug in API)

app/Handlers/Commands/ComponentGroup/RemoveComponentGroupCommandHandler.php

@@ -0,0 +1,40 @@
+<?php
+
+/*
+ * This file is part of Cachet.
+ *
+ * (c) Alt Three Services Limited
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace CachetHQ\Cachet\Handlers\Commands\ComponentGroup;
+
+use CachetHQ\Cachet\Commands\ComponentGroup\RemoveComponentGroupCommand;
+use CachetHQ\Cachet\Events\ComponentGroup\ComponentGroupWasRemovedEvent;
+use CachetHQ\Cachet\Models\ComponentGroup;
+
+class RemoveComponentGroupCommandHandler
+{
+    /**
+     * Handle the remove component group command.
+     *
+     * @param \CachetHQ\Cachet\Commands\ComponentGroup\RemoveComponentGroupCommand $command
+     *
+     * @return void
+     */
+    public function handle(RemoveComponentGroupCommand $command)
+    {
+        $group = $command->group;
+
+        event(new ComponentGroupWasRemovedEvent($group));
+
+        // Remove the group id from all component.
+        $group->components->map(function ($component) {
+            $component->update(['group_id' => 0]);
+        });
+
+        $group->delete();
+    }
+}