Bug 20140: Allow translating more of OAI sets

Bug 20140: Allow translating more of OAI sets

Allow translating two strings in the OAI set config:
"setDescription" and "Remove"

Test plan:

1) Go to Home -> Administrator -> OAI sets config -> Add a new OAI set
2) Click on "New set"
3) Click on "Add description"
4) Note the "setDescription:" and "Remove" -texts
5) Install patch, update language, translate the new strings
6) Redo 1-4, note how the strings in part 4 are now translated

Signed-off-by: Pasi Kallinen <pasi.kallinen@joensuu.fi>
Signed-off-by: Roch D'Amour <roch.damour@inlibro.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>