Add first, basic version of info command

This will hopefully help in debugging some problems.

src/Console/Server.php

@@ -36,6 +36,7 @@ class Server extends AbstractServer
 
         $console->add($app->make('Flarum\Install\Console\InstallCommand'));
         $console->add($app->make('Flarum\Update\Console\MigrateCommand'));
+        $console->add($app->make('Flarum\Debug\Console\InfoCommand'));
         $console->add($app->make('Flarum\Console\Command\GenerateExtensionCommand'));
         $console->add($app->make('Flarum\Console\Command\GenerateMigrationCommand'));
 

src/Debug/Console/InfoCommand.php

@@ -0,0 +1,59 @@
+<?php
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Debug\Console;
+
+use Flarum\Console\Command\AbstractCommand;
+use Flarum\Extension\ExtensionManager;
+use Flarum\Foundation\Application;
+
+class InfoCommand extends AbstractCommand
+{
+    /**
+     * @var ExtensionManager
+     */
+    protected $extensions;
+
+    /**
+     * @param ExtensionManager $extensions
+     */
+    public function __construct(ExtensionManager $extensions)
+    {
+        $this->extensions = $extensions;
+
+        parent::__construct();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function configure()
+    {
+        $this
+            ->setName('info')
+            ->setDescription("Gather information about Flarum's core and installed extensions");
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function fire()
+    {
+        $this->info('Flarum core '.Application::VERSION);
+
+        foreach ($this->extensions->getEnabledExtensions() as $extension) {
+            /** @var \Flarum\Extension\Extension $extension */
+            $name = $extension->getId();
+            $version = $extension->getVersion();
+
+            $this->info("EXT $name $version");
+        }
+    }
+}