fixed some migration names and used helper where appropriate

framework/core/migrations/2018_01_15_071700_change_user_discussions_discussions_users.php

@@ -9,14 +9,6 @@
  * file that was distributed with this source code.
  */
 
-use Illuminate\Database\Schema\Builder;
+use Flarum\Database\Migration;
 
-return [
+return Migration::renameTable('users_discussions', 'discussions_users');
-    'up' => function (Builder $schema) {
-        $schema->rename('users_discussions', 'discussions_users');
-    },
-
-    'down' => function (Builder $schema) {
-        $schema->rename('discussions_users', 'users_discussions');
-    }
-];

framework/core/migrations/2018_01_15_072600_change_email_tokens_b8_columns.php

@@ -1,27 +0,0 @@
-<?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.
- */
-
-use Illuminate\Database\Schema\Blueprint;
-use Illuminate\Database\Schema\Builder;
-
-return [
-    'up' => function (Builder $schema) {
-        $schema->table('email_tokens', function (Blueprint $table) {
-            $table->renameColumn('id', 'token');
-        });
-    },
-
-    'down' => function (Builder $schema) {
-        $schema->table('email_tokens', function (Blueprint $table) {
-            $table->renameColumn('token', 'id');
-        });
-    }
-];

framework/core/migrations/2018_01_15_072600_change_email_tokens_rename_id_to_token.php

@@ -0,0 +1,14 @@
+<?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.
+ */
+
+use Flarum\Database\Migration;
+
+return Migration::renameColumn('email_tokens', 'id','token');

framework/core/migrations/2018_01_18_130400_rename_users_groups_to_groups_users.php

@@ -11,4 +11,4 @@
 
 use Flarum\Database\Migration;
 
-return Migration::renameTable('users_groups', 'group_user');
+return Migration::renameTable('users_groups', 'group_users');