Revert "*: providers and sources -> channels, PolicyModel to PolicyBindingModel that uses custom M2M through"

This reverts commit 7ed3ceb960.

passbook/core/api/providers.py

@@ -0,0 +1,30 @@
+"""Provider API Views"""
+from rest_framework.serializers import ModelSerializer, SerializerMethodField
+from rest_framework.viewsets import ReadOnlyModelViewSet
+
+from passbook.core.models import Provider
+
+
+class ProviderSerializer(ModelSerializer):
+    """Provider Serializer"""
+
+    __type__ = SerializerMethodField(method_name="get_type")
+
+    def get_type(self, obj):
+        """Get object type so that we know which API Endpoint to use to get the full object"""
+        return obj._meta.object_name.lower().replace("provider", "")
+
+    class Meta:
+
+        model = Provider
+        fields = ["pk", "property_mappings", "__type__"]
+
+
+class ProviderViewSet(ReadOnlyModelViewSet):
+    """Provider Viewset"""
+
+    queryset = Provider.objects.all()
+    serializer_class = ProviderSerializer
+
+    def get_queryset(self):
+        return Provider.objects.select_subclasses()