Refactor body class from controllers to template

WEBSITE-1158
Refactor template assignment to routing yml instead of controllers

For pages that don't require a controller function

WEBSITE-1158
Use StaticTemplateController for caching

WEBSITE-1158
Fix getInvolved route

WEBSITE-1158
Merge pull request #43 from PayBas/task/refactor-header-images

Refactor body class from controllers to template