Bug 37580: Unique Holidays Description are not editable

Bug 37580: Unique Holidays Description are not editable

Holiday names and descriptions are not editable after creation in
    tools/holiday.pl.
This patch corrects this regression.

To test:

1) Login to staff client
2) Open Tools -> Calendar
3) Click on a date and create a holiday with name and description.
4) Save holiday.
5) Click on newly created holiday on calendar and edit the name and
   description.
6) Re-Save Holiday.
7) Click again on holiday, and see that name and description changes
   did not save.
8) Apply patch
9) Repeat steps 5-7
10) Verify that changes now save.

Sponsored-by: Westlake Porter Public Library
Signed-off-by: Martha <msulllivan@rcls.org>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>