Add version checking to daemon and panel

Also includes some buttons for users to get help from the panel.

app/Services/VersionService.php

@@ -0,0 +1,93 @@
+<?php
+/**
+ * Pterodactyl - Panel
+ * Copyright (c) 2015 - 2016 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\Services;
+
+use Cache;
+use GuzzleHttp\Client;
+
+class VersionService
+{
+
+    protected static $versions;
+
+    /**
+     * Constructor
+     */
+    public function __construct()
+    {
+        self::$versions = Cache::remember('versions', env('VERSION_CACHE_TIME', 60), function () {
+            $client = new Client();
+
+            try {
+                $response = $client->request('GET', env('VERSION_CHECK_URL', 'https://cdn.pterodactyl.io/releases/latest.json'));
+
+                if ($response->getStatusCode() === 200) {
+                    return json_decode($response->getBody());
+                } else {
+                    throw new \Exception('Invalid response code.');
+                }
+            } catch (\Exception $ex) {
+                // Failed request, just return errored version.
+                return (object) [
+                    'panel' => 'error',
+                    'daemon' => 'error',
+                ];
+            }
+        });
+    }
+
+    public static function getPanel()
+    {
+        return self::$versions->panel;
+    }
+
+    public static function getDaemon()
+    {
+        return self::$versions->daemon;
+    }
+
+    public function getCurrentPanel()
+    {
+        return config('app.version');
+    }
+
+    public static function isLatestPanel()
+    {
+        if (config('app.version') === 'canary') {
+            return true;
+        }
+
+        return (version_compare(config('app.version'), self::$versions->panel) >= 0);
+    }
+
+    public static function isLatestDaemon($daemon)
+    {
+        if ($daemon === '0.0.0-canary') {
+            return true;
+        }
+
+        return (version_compare($daemon, self::$versions->daemon) >= 0);
+    }
+
+}