Avoid using {...} for multi-line blocks
Render the correct footer on the error page

Adding a test also as twice in the last week the 404 page has been giving a 500
in production
Merge pull request #625 from moneyadviceservice/fix-error-page-again

Render the correct footer on the error page
A set of classes to encapsulate details for mounting engines.

Setup for our first engine, pensions calculator, with a pattern that can be expanded for other engines.
Implement the language translation link and alternate meta tags for engines.
Implement correct constraints for the pensions calculator.