Allow admins to change contents of the landing page.
* Top-left side
* Closed-registration messageRest of the page
Each piece of information should be stored in the `appcontent` table, each with their own `id` and `content_type`, e.g.
| Element | `id` | `content_type` |
| --- | --- | --- |
| Top-left side | `landing-banner` | `section` |
| Rest of the page | `landing-body` | `section` |
* Rest of the pageThis should probably be editable as a special page under the Admin > Pages section. It could include two separate textareas, one for editing the top-left side and one for editing the rest of the page.
If we store this information in the `appcontent` tableThe landing template should be changed to render this stored data instead of the default page, we'll want to add a new field: `is_much like About and Privacy page`,s do. so we can later support dynamic instance-level static pagesThe app should fall back to the current templated information if custom data for these sections aren't stored in the database yet.