Update the header footer only template

- The titles in the footer were inheriting the core-24 styles from
  elsewhere. Forced them to manually have the core-24 style
- Removed all but the core javascript. This ensures the analytics still
  works.
- Added some extra CSS files to the header footer stylesheet as they are
  required to make the header footer work properly
Merge pull request #190 from alphagov/header-footer-only

This is a great pull request.