Customisable tenant landing pages

Customisable tenant landing pages excluding edit UI
Probably super-minor but,
[From the docs](http://api.jquery.com/header-selector/)
> Because :header is a jQuery extension and not part of the CSS specification, queries using :header cannot take advantage of the performance boost provided by the native DOM querySelectorAll() method. To achieve the best performance when using :header to select elements, first select the elements using a pure CSS selector, then use .filter(":header").

so maybe we should do:
```javascript
$('.index-block-' + blockIndex).filter(':header').css('color', block.titleColor);
```