Bug 19670: Change Collation of marc_field to allow mixed case mappings

Bug 19670: Change Collation of marc_field to allow mixed case mappings

Test plan:
1. Apply patch and update database
2. Verify that you can add a search field mapping for both 100a and 100A.
3. Verify that the above also works with a newly-created database.

Signed-off-by: Michal Denar <black23@gmail.com>

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
(cherry picked from commit a5f3d405f56202beb4426da52f3bf4019f26484b)
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>