user: fix populate for dev and use native django function to fetch payment_method

subscription/models.py

@@ -25,7 +25,6 @@
 from datetime import date, timedelta
 from django.db import models
 from django.utils import timezone
-from ast import literal_eval as make_tuple
 from django.utils.translation import ugettext_lazy as _
 from django.conf import settings
 from django.core.exceptions import ValidationError
@@ -72,10 +71,6 @@ class Subscription(models.Model):
         verbose_name=_("location"),
     )
 
-    def get_payment_method_display(self):
-
-        return _(make_tuple(self.payment_method)[1])
-
     class Meta:
         ordering = ["subscription_start"]