Bug 17359: Correct encoding when displaying patron import summary

Bug 17359: Correct encoding when displaying patron import summary

There is an encoding issue when the patron import summry, the string
must be UTF8 decoded before being sent to the template.

Test plan:
- Create a patron import CSV file with import issues. Use UTF8 characters.
See file attached to the bug report 'patron_import.csv'
=> The screen should display the line correctly
- Correct the import issue (add a surname for Chloé)
=> The imported patrons should contain the correct values.

Signed-off-by: Séverine QUEUNE <severine.queune@bulac.fr>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>