Adding Gift Card

To add gift cards:

• add it as an option in researcher_UI.models.payment_code.PaymentCode.PAYMENT_TYPE_CHOICES
• add appropriate validation in researcher_UI.utils.raw_gift_codes.get_gift_card_regex
• add appropriate urls in cdi_form.views.administration_views.AdministrationSummaryView.
• amend content presented to users as appropriate in cdi_forms.templates.cdi_forms.administration_summary.html