Add base implementation of extendable events classes

Modified server deletion to use internal event handlers from the
Eloquent models themselves. Also added a few preliminary event handlers
in the `Pterodactyl\Events\<USer|Server> namespace that users can hook
into in EventServiceProvider to perform their own actions as they
please (such as push notifications and such).

app/Events/Server/Created.php

@@ -0,0 +1,45 @@
+<?php
+/**
+ * Pterodactyl - Panel
+ * Copyright (c) 2015 - 2017 Dane Everitt <dane@daneeveritt.com>.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+namespace Pterodactyl\Events\Server;
+
+use Pterodactyl\Models\Server;
+use Illuminate\Queue\SerializesModels;
+
+class Created
+{
+    use SerializesModels;
+
+    public $server;
+
+    /**
+     * Create a new event instance.
+     *
+     * @return void
+     */
+    public function __construct(Server $server)
+    {
+        $this->server = $server;
+    }
+}