Bug 18160 - Error when OverDriveCirculation not enabled

Bug 18160 - Error when OverDriveCirculation not enabled

This patch only executes OverDrive circulation JS if
OverDriveCirculation pref is enabled

To test:
1 - Disable OverDriveCirculation
2 - Log in to opac and view summary tab
3 - Note 'Internal server error'
4 - Apply patch
5 - Repeat and note error is not present

Signed-off-by: Srdjan <srdjan@catalyst.net.nz>
Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>