Fix for query strings being stripped

This ensures query strings aren't stripped when we redirect to ensure a trailing slash. This looks like an unintentional bug rather than intentional design as query strings do work with a trailing slash, e.g.

Broken

test.gitlab-example.com/search?q=test which redirects to test.gitlab-example.com/search/

Working

test.gitlab-example.com/search/?q=test

This MR corrects the behaviour of the redirect to add the trailing slash by re-appending the query string.

Resolves #191 (closed)