from and to dates in orders list view whe filtering are now format_d…

[svandeneertwegh]

Date from and date in dashboard are now ready with format_datetime.

Below List Views are already working with the format_datetime function:

• oscar/apps/dashboard/reviews/views.py
• oscar/apps/dashboard/reports/views.py

Only the orders filtering list view doesn't: (therefor this PR)

• oscar/apps/dashboard/orders/views.py