Bug 21846: Make 'term' use utf8mb_bin collation on tags tables

Bug 21846: Make 'term' use utf8mb_bin collation on tags tables

This patch makes the utf8mb4_bin collation preferred for comparing tags.
Otherwise suppolemental unicode characters all match.

To test:

- Enable tags and disable moderation (or plan to moderate and accept tags)
- Tag 3 records:
   a - with 🐋
   b - with 🌮
   c - with 👍
- Note the weight on each says '3'
- Click the tag to search, you get back all the records
- Apply the previous patches from this bug report
- Run:
  $ kshell
 k$ prove t/db_dependent/Tags.t
=> FAIL: Tests fail, related to counting stuffs
- Apply this patch and
(a) Run updatedatabase to upgrade the schema
- Run:
 k$ prove t/db_dependent/Tags.t
=> SUCCESS: Tests pass!
(b) reset_all to get a fresh DB using kohastructure.sql
- Run:
 k$ prove t/db_dependent/Tags.t
=> SUCCESS: Tests pass too!
- Sign off :-D

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>