Urlencode reservation ids

Currently, if a reservation name contains special characters for a URL,
the reservation URL won't work and we will get "Sorry, but the
reservation you are trying to use seems to be invalid or expired."

That's because sanitize_title_with_dashes urlencodes the data,
but all the request variables are automatically decoded and when we
compare them they don't match.
Don't sanitize reservations ids and tokens

sanitizer_text_field removes urlencoded %-based octets, which are
sometimes valuable information. In our case – we have token ids in
Cyrillic.
Merge branch 'urlencode-reservation-id' of https://github.com/nb/camptix into 68