Remove MyISAM Requirement (#2442)

- Remove Database Engine Default of InnoDB
- Remove Hard Coded MyISAM requirement

framework/core/migrations/2015_02_24_000000_create_posts_table.php

@@ -30,8 +30,6 @@ return [
             $table->integer('hide_user_id')->unsigned()->nullable();
 
             $table->unique(['discussion_id', 'number']);
-
-            $table->engine = 'MyISAM';
         });
 
         $connection = $schema->getConnection();