This adds a new field "Can be guarantee" to patron categories so it
becomes possible for any category type to have a guarantor.
1) Have a patron category of type 'Adult' and one of type 'Child'
2) Confirm, by searching for the "Patron guarantor" fieldset in the
edit/create form, that:
=> a patron of the first category can't have a guarantor
=> a patron from the second category can
3) Apply patch and run updatedatabase.pl
4) Edit the categories and note the new "Can be guarantee" field
5) It should have been set to "yes" for the "Child" and to "no" for
5) Repeat step 2. It should behave in the same way.
6) Edit the "Can be guarantee" for any of the category and check
that the fieldset only appears when "Can be guarantee" is set to "yes"
7) prove t/db_dependent/Patrons.t
=> tests should still pass