FE: Move GA to head
Remove unused `state-templates` code
FE: Use `strong` instead of quotes

As the text highlighted is what user is expected to type it helps
to reduce vagueness by removing the quotes in case user thinks
it's part of the case.
FE: Add static template 500 error template
Update nginx config to include 500 error pages location
Merge pull request #313 from ministryofjustice/feature/error-pages

Feature/error pages