donate: Set fixed amounts per project

donate/migrations/0010_auto_20200902_1744.py

donate/models.py

donate/templates/donate/donate_home_page.html

donate/templates/donate/donate_info_page.html

donate/templates/donate/donate_project_page.html

donate/templates/donate/donate_region_page.html

donate/templates/donate/donate_targeted_donations_page.html