Allow blocks to be easily loaded during Authcache Ajax phase (aka Ajaxify Regions)

The Authcache Example module demonstrates how dynamic/user-centric blocks can be loaded during the Ajax phase. Many users do not understand or are not capable of implementing this code, however, so this feature should be built into Authcache for better ease-of-use.

This functionality would be similar to the Ajaxify Regions module (http://drupal.org/project/ajaxify_regions), but built into Authcache config/JS with improved caching performance.

A checkbox and cache lifetime text field would be added to the block configuration screen.