Add method for building absolute URI w/out request

gracedb/core/urls.py

+# URL utilities
+
+from django.contrib.sites.models import Site
+
+def build_absolute_uri(relative_uri, request=None):
+    if request is not None:
+        return request.build_absolute_uri(relative_uri)
+    else:
+        # Assume HTTPS
+        domain = Site.objects.get_current().domain
+        return 'https://' + domain + relative_uri