Bug 6479 Converts all the serialseq variables to UTF-8.

Bug 6479 Converts all the serialseq variables to UTF-8.

Corrects a problem when an UTF-8 character is used in the serial
numbering formula. The encoding became incorrect when concatenating the
number in the subscriptionhistory table.

Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
To reproduce:
- Create subscription with numbering pattern N° {X}
- Receive 2 or more issues
- Check subscription summary page and manual history fields on the edit screen

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>