Bug 16772 - Change label from 'For:' to 'Library:' to ease translation

Bug 16772 - Change label from 'For:' to 'Library:' to ease translation

This patch changes the label from "For:" to "Library:" in the
acquisition information filter on the suggestions page in staff client.

To test:
- Apply patch
- Go to Home > Acquisitions > Suggestions management
- Verify that label reads as appropriate (in filter
  Acquisition information)

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>