Bug 19702: Correct cookie path in Basket.js

Bug 19702: Correct cookie path in Basket.js

This corrects the cookie path in bootstrap/js/basket.js. It used to take
the default value (current page path), but will now be "/"

Test plan:
0) Visit the OPAC, add a book to your basket
1) Navigate to the OPAC's homepage (www.domain.com, without the
    /cgi-bin/koha)
    -> The basket will display as empty
    2) Apply patch
    3) Clear your cookies and your cache
    4) Redo step 1)
        -> Basket will display correctly

Patch applies without issue and functions as descibed.
Signed-off-by: Dilan Johnpullé <dilan@calyx.net.au>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>