[IMP] hr and its related modules improvements

addons/hr/__openerp__.py

addons/hr/hr.py

addons/hr/hr_demo.xml

addons/hr/hr_department.py

addons/hr/hr_department_demo.xml

addons/hr/hr_view.xml

addons/hr/test/test_hr.yml

addons/hr_holidays/report/holidays_summary_report.py

addons/hr_holidays/wizard/hr_holidays_summary_department.py

addons/hr_holidays/wizard/hr_holidays_summary_employees.py

addons/hr_timesheet/hr_timesheet_demo.xml

...r_timesheet_invoice/report/hr_timesheet_invoice_report.py

addons/hr_timesheet_sheet/hr_timesheet_sheet.py

addons/stock_planning/stock_planning.py