abra.sh: add get_user_uid() command

abra.sh

@@ -242,3 +242,9 @@ cert = saml.signing_kp
 print(''.join(cert.certificate_data.splitlines()[1:-1]))
 """ 2>&1 | quieten
 }
+
+get_user_uid() {
+/manage.py shell -c """
+print(User.objects.filter(username='$1').first().uid)
+""" 2>&1 | quieten
+}