Bug 17720: CSRF - Handle unicode characters

Bug 17720: CSRF - Handle unicode characters

From the pod of Digest::MD5:
"""
Since the MD5 algorithm is only defined for strings of bytes, it can not
be used on strings that contains chars with ordinal number above 255
(Unicode strings). The MD5 functions and methods will croak if you try
to feed them such input data.
What you can do is calculate the MD5 checksum of the UTF-8
representation of such strings.
"""

Test plan:
- Set a MySQL/MariaDB password with unicode characters:
  UPDATE user SET password=PASSWORD('❤') WHERE USER='koha_kohadev';
  FLUSH PRIVILEGES
- Update your $KOHA_CONF file
- Restart Memcached
- Hit the files modified by this patch

=> Without this patch, you will get a software error (with "Wide
character in subroutine entry" in the logs).
=> With this patch, everything will go fine

Signed-off-by: Josef Moravec <josef.moravec@gmail.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Edit: removed debugging leftover

Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>