Replace YAML fixtures with JSON fixtures

fixtures/auth/group.json

fixtures/auth/group_permissions.json

fixtures/auth/user.json

fixtures/auth/user_groups.json

fixtures/program/category.json

fixtures/program/fundingcategory.json

fixtures/program/host.json

fixtures/program/language.json

fixtures/program/musicfocus.json

fixtures/program/rrule.json

fixtures/program/show.json

fixtures/program/topic.json

fixtures/program/type.json

program/fixtures/categories.yaml

program/fixtures/fundingcategories.yaml

program/fixtures/group_permissions.yaml

program/fixtures/groups.yaml

program/fixtures/hosts.yaml

program/fixtures/languages.yaml

program/fixtures/musicfocus.yaml