Bug 11944: Fix encoding issue on adding a subscription

Bug 11944: Fix encoding issue on adding a subscription

If frequencies or numbering patterns contain non-latin characters, so
output was broken.

To reproduce:
- Create a frequency and a numbering pattern with non-latin characters
- Add a new subscription using these values
- The screen should not contain bad encoded characters.

Signed-off-by: Paola Rossi <paola.rossi@cineca.it>
Signed-off-by: Bernardo Gonzalez Kriegel <bgkriegel@gmail.com>
Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>