Bug 13856: Hard to translate strings on patron search results page

Bug 13856: Hard to translate strings on patron search results page

'Add selected patrons to:' at the top of the patron search result
table is hard to translate correctly, because the 'to:' appears
as a separate string from the rest of the sentence.

To test:
- Make sure patron lists are activated
- Do a patron search with more than 1 result
- Look for the text at the top of the search results table
- Verify it looks the same before and after the patch

Bonus:
- run perl translate update <langcode> and verify the
  2 strings are now 1 string with the patch applied

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>