Bug 27581: Rename USeICU preference to UseICUStyleQuotes

Bug 27581: Rename USeICU preference to UseICUStyleQuotes

Rather thna have a poorly named preference with an explanation of how it doesn't
do what it implies it does, let's rename it!

To test:
 1 - Set UseICU to 'Using'
 2 - Go to the details page of a record in the staff interface
 3 - Hover over a subject heading that has subfields
 4 - Note the link has curly brackets around the subject, like:
     http://localhost:8081/cgi-bin/koha/catalogue/search.pl?q=su:{Winnie-the-Pooh Fictitious character}
 5 - Change UseICU to 'Not using'
 6 - Note the link is now:
     http://localhost:8081/cgi-bin/koha/catalogue/search.pl?q=su:"Winnie-the-Pooh Fictitious character"
 7 - Repeat on OPAC
 8 - Apply patch
 9 - Restart all
10 - Repeat tests, the behaviour has not changed
11 - Read the new syspref description and confirm it makes sense

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>