Bug 20124: Make "Save configuration" translatable on "did you mean?" config

Bug 20124: Make "Save configuration" translatable on "did you mean?" config

When saving the "Did you mean?" setting, a popup with the
message "Successfully saved configuration" is shown, but
it cannot be translated. Make it translatable.

Test plan:

1) Go to Home -> Administration -> Did you mean?
2) Change the settings, click on "Save configuration"
3) Popup with "Successfully saved configuration"
4) Apply patch, update po-files, etc.
5) Check that the msgid "Successfully saved configuration"
   is in fi-FI-staff-prog.po, and translate the message
6) install the fi-FI language
7) Change your UI language to finnish
8) Repeat 1, 2, 3. You should now see the same popup
   message translated.

Signed-off-by: Pasi Kallinen <pasi.kallinen@joensuu.fi>
Signed-off-by: Roch D'Amour <roch.damour@inlibro.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>