Bug 11944: Fix encoding issue on search history

Bug 11944: Fix encoding issue on search history

Newly introduced by patches from bug 10807, the string was decoded
before to be stored in session.

To reproduce:
Enable history search
Go at the OPAC and log out
Search for something with utf-8
Go on your search history
The search description should be correctly encoded

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Dobrica Pavlinusic <dpavlin@rot13.org>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>