Add new app 'help' for user support

This commit adds a new model that enhances the user profile with an
offline support code, a postal address and an email address to allow
users to reset their profile.

The commit adds to Django admin commands 'populate' and
'reset_offline_code' to maintain the help user profiles from the Django
command line.

gnuviechadmin/help/models.py

@@ -0,0 +1,17 @@
+import uuid
+
+from django.conf import settings
+from django.db import models
+from django.utils.translation import ugettext_lazy as _
+
+
+class HelpUser(models.Model):
+    user = models.OneToOneField(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
+    email_address = models.EmailField(help_text=_("Contact email address"))
+    postal_address = models.TextField(help_text=_("Contact postal address"), blank=True)
+    offline_account_code = models.CharField(
+        help_text=_("Offline account reset code"), max_length=36, default=""
+    )
+
+    def generate_offline_account_code(self):
+        self.offline_account_code = str(uuid.uuid4())