appendix header spacing and search ajax bug

This pull request does three things:

* Adjusts the margin on headers in the appendix (including headers that have no content after them)
* Fixes the ajax search request bug that prevented searching on a revision other than the current one
* Adds an event handler to update the effective date of a regulation in the subhead

The event handler is somewhat messy, somebody more familiar with the codebase than I am may want to refactor it (or talk me through doing same).