Currently the translation:
"Notify me by email when someone comments on my proposals or debates"
It only refers to proposals and debates, but actually it also refers to budget
investments, topics and polls.
The user can access this page without being logged in.
We identify the user through the "subscriptions_token" parameter and
show a list of the notifications that can be enable/disable.
We will return a 404 error in case someone accesses the page with a
non-existent token.
We also control the case that some anonymous user tries to access the
page without any token, by returning the CanCan::AccessDenied exception.
