HR Holidays(Summary Department) Report crash with some locale

[Hervé Martinet]

In method create_xml of class report_custom (hr_holidays/report/holidays_summary_report.py), the call of som.strftime('%B') will return 'août' in a utf-8 string if your system locale is FR.UTF8. This will generate a crash on the date_xml = ''.join(date_xml) instruction, which operate on ACSII string !

This bug causes an error in yaml test for some locale and some month of the year. %B return the full month name in system locale, which is UTF8 by default on linux systems.

Environment to reproduce:

System: Ubuntu 12.04 LTS
System locale : fr_CH.UTF-8
OpenERP : 7.0 launchpad serie (server revision 5058 / addons revision 9386 / web revision 4020)

tests run with : server/openerp-server --addons-path=addons,web/addons -d ***** --db_user=***** --db_password=***** --db_host=localhost --db_port=5432 -u hr_holidays --log-level=test --test-enable