add trailing slash for category url

[ghost]

In your blog, there is a _elixir_ category, and its url is (http://andreimihu.com/categories/elixir). But when I clicked it, browser is redirected to (http://andreimihu.com/categories/elixir/).

I guess it's some magic like nginx url rewrite. Since in the post-generated public folder, _elixir_ is definely a foder, will you please enable trailing slash as the default.