Friendlier admin menu structure

As it is, unless you go to the modules page and click the "configure" button next to the Redhen module, it's not immediately obvious how to configure RedHen. There's also no set structure on how contributed modules extending RedHen will incorporate themselves and their configuration settings.

I propose exposing a "Redhen CRM" section on Drupal's main configuration page, under which there would be a single default item (the existing configuration page, which would move to admin/config/redhen/crm). Other modules would create additional normal menu items at admin/config/redhen/foo, and they'd automatically show up in this section.

Patch and screenshot attached.