Update world location page for new contact markup

The markup on world office contacts changed yesterday. This brings the
styles inline with the new changes.

I also did the following tiding:
- remove the class `document-grid` from the world offices block as its not a
  document grid.
- Move the office heading inside the section. Semantically headings
  should be inside sections not above them
- Update the word departments to offices. They aren't departments.
- Remove padding from the bottom of every block. There was far to much
  padding everywhere. It can be put back in on a block by block case.