It fixes Rails 5.0 deprecation flooding like:
```
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references. For example:
"::Gitlab::Middleware::ReadOnly" => Gitlab::Middleware::ReadOnly
(called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references. For example:
"ActionDispatch::Static" => ActionDispatch::Static
(called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references. For example:
"Gitlab::Testing::RequestBlockerMiddleware" => Gitlab::Testing::RequestBlockerMiddleware
(called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references. For example:
"ActionDispatch::Static" => ActionDispatch::Static
(called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references. For example:
"Gitlab::Testing::RequestInspectorMiddleware" => Gitlab::Testing::RequestInspectorMiddleware
(called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
```