Bug 28845: Match against the full limit string, not just the group id

Bug 28845: Match against the full limit string, not just the group id

To test:
1 - Add to OPAC virtual host in apache conf:
   SetEnv OPAC_SEARCH_LIMIT branch:multibranch-1
   SetEnv OPAC_LIMIT_OVERRIDE 1
   RequestHeader add X-Koha-SetEnv "OPAC_SEARCH_LIMIT branch:multibranchlimit-1"
   RequestHeader add X-Koha-SetEnv "OPAC_LIMIT_OVERRIDE 1"
2 - Enable system preference OpacAddMastheadLibraryPulldown
3 - Create a library group enabled as OPAC search group (or make sure existing group 1 is an OPAC search group)
4 - Load the opac - dropdown does not pree-select the search group
5 - Apply patch
6 - Relaod opac - group is pre-selected!

Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Joonas Kylmälä <joonas.kylmala@iki.fi>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>