When the `multitenancy_management_mode` is enabled.
In order to avoid infinite redirects when regular users try to access
the admin section, we're redirecting to the account page in this case.
Otherwise, the admin section would redirect to the root path, which
would redirect to the admin section, which would redirect to the root
path, and so on.
In general, we always use relative URLs (using `_path`), but sometimes
we were accidentally using absolute URLs (using `_url`). It's been
reported i might cause some isuses if accepting both HTTP and HTTPS
connections, although we've never seen the case.
In any case, this change makes the code more consistent and makes the
generated HTML cleaner.
We were raising a `CanCan::AcessDenied` and were getting a 500 Internal
Server Error.
I've chosen to do the same thing we do in the ApplicationController.
There are other options to handle this request, like redirecting to the
login page or returning a 401 Unauthorized HTTP status.
