Bug 25672: Enable enable_plugin_browser_upload by default

Bug 25672: Enable enable_plugin_browser_upload by default

This patch enables enable_plugin_browser_upload by default,
since the current behaviour for Koha is to enable browser upload
when enable_plugins is 1.

Signed-off-by: Nicolas Legrand <nicolas.legrand@bulac.fr>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: David Cook <dcook@prosentient.com.au>
Signed-off-by: Victor Grousset/tuxayo <victor@tuxayo.net>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>