Bug 20166: Untranslatable course reserves delete prompt

Bug 20166: Untranslatable course reserves delete prompt

Having a Template Toolkit statements inside the javascript
translation function _() prevents it from being picked for
translation.

The only example of such is the course reserve delete prompt.
Move the TT statement outside the string.

Test plan:

1) Update and install language xx-YY. Check that the msgids
   "Are you sure you want to delete this course? There is %s attached item."
   and
   "Are you sure you want to delete this course? There are %s attached items."
   do not exist in the xx-YY-staff-prog.po
2) Check the translated file
   intranet-tmpl/prog/fi-FI/modules/course_reserves/course-details.tt
   It should have two prompt texts above in English
3) Install patch
4) Update the language. Check that the msgids show up in
   xx-YY-staff-prog.po, translate them, and install the language.
5) Repeat 2, the prompts should now show up in the correct language.
6) Enable UsecourseReserves
7) Go to Home -> Course reserves
8) Create a new course, and add reserves to it
9) See the course details. Click on Delete course, the prompt
   should be correctly translated
10) Remove all but one of the reserves from the course
11) Repeat 9

To see if there are other such TT statements:

    rgrep -E '\b_\("[^"]*\[%' koha-tmpl/

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>