Bug 13656: "Change"/"Set to patron" button for linking a member to an organisation...

Bug 13656: "Change"/"Set to patron" button for linking a member to an organisation (or child to guarantor) not translatable

Test plan:
1. install and activate an additional language
2. create patron in organization category
3. create professional patron
4. try to add this patron to an organization (Guarantor information section)
5. note that the left button text changed to "Change" - untranslated english string
6. push the "Delete" button, the guarantor patron field is cleared and the left button text changed to "Set to patron" - again original english text
7. apply the patch
7.1. update translation (koha-translate -u language_code)
8. repeat 4-6, note, that button text are still translated in all sitations
9. sign off ;)

Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Work as described, no errors
Fixed message capitalization

Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>