Bug 17216: Add new table authorised_value_categories and populate it

Bug 17216: Add new table authorised_value_categories and populate it

This patch set adds a new table authorised_value_categories to store
authori(s|z)ed value categories into a separate table.
The problematic is explained on bug 15799 comment 4:
We need FK to the AV categories but some may not have authorized values
yet.

What does this patch set:
- Add a new authorised_value_categories table
- Populate it with known categories
- Update FK items_search_fields.authorised_values_category
- Create a new FK marc_subfield_structure.authorised_value (FIXME should
  be authorised_value_categories instead)

They are some problems this patch set do not take into account:
- The .sql installer files won't insert correctly (will have to be
  updated when this patch set will be ready to be pushed)
- All the categories (even the ones without authorized values defined)
  are listed when you edit frameworks (marc_subfield_structure.pl)
- There is no way to delete a category (TODO). But to do so it would be
  good to have a authorised_value_categories.is_internal field to mark
  some categories as "cannot be deleted".

Test plan:
0/ Execute the DB entry to create and populate the new table and set the FK
1/ Create a new AV category from the admin module (admin/authorised_values.pl)
2/ Add/edit subfield linked to a AV category
(admin/marc_subfield_structure.pl)
3/ You won't be allowed to add AV for branches, itemtypes or cn_source.
They are used internally.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer  <katrin.fischer@bsz-bw.de>
Signed-off-by: Brendan Gallagher <brendan@bywatersolutions.com>