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

This reverts commit 7ed3ceb960.

passbook/providers/saml/utils/__init__.py

@@ -0,0 +1,18 @@
+"""Small helper functions"""
+import uuid
+
+from django.http import HttpRequest, HttpResponse
+from django.shortcuts import render
+from django.template.context import Context
+
+
+def render_xml(request: HttpRequest, template: str, ctx: Context) -> HttpResponse:
+    """Render template with content_type application/xml"""
+    return render(request, template, context=ctx, content_type="application/xml")
+
+
+def get_random_id() -> str:
+    """Random hex id"""
+    # It is very important that these random IDs NOT start with a number.
+    random_id = "_" + uuid.uuid4().hex
+    return random_id