2. Add site configuration overrides to theming/helpers.py
3. Move microsite.get_value from theming/helpers to site_configuration/helpers
4. Move microsite_configuration.microsite.get_value usages to site_configuration.helpers.values
Add configuration model for enrollment refunds.
Use order info from otto in refund window calculation
Delete dupe tests. Extend tests to include window tests
Move ecom client from lib to djangoapps in openedx