Added date configuration to Schedule & Details settings page

[jbcurtin]

Description

Adds the ability to configure Schedule & Details settings page with the ability to show dd/mm/yyyy format. Default setting maintains existing behavior and doesn't introduce anything new.
Why:
Some areas of the world operate with the day-first: dd/mm/yyyy rather than mm/dd/yyyy.

Useful information to include:

• No change to role(s)
• There is no before or after, as the change includes default configuration to remain consistent with preexisting behavior.
• https://github.com/open-craft/edx-platform/blob/jbcurtin/bb-5429-date-configuration/cms/envs/common.py#L459

Testing instructions

• Initialize devstack to use branch
• Open file cms/env/common.py and find SCHEDULE_DETAIL_FORMAT. Alter the string value from mm/dd/yyyy -> dd/mm/yyyy.
• Load Schedule & Details page ( http://localhost:18010/settings/details/course-v1:edX+DemoX+Demo_Course )
• Scroll down to Course Schedule. Notice the placeholder format in the date-fields.
• Click in various date-fields and make sure the dates are correctly applied in format: dd/mm/yyyy

Deadline

None as of now.

[farhaanbukhsh]

Closing in favour of #458