Fix timezone warnings if USE_TZ=True

import datetime

from django.db import models

from django.db.models.loading import BaseAppCache

from django.utils.timezone import now

class MigrationRecorder(object):

    class Migration(models.Model):

        app = models.CharField(max_length=255)

        name = models.CharField(max_length=255)

        applied = models.DateTimeField(default=datetime.datetime.utcnow)

        applied = models.DateTimeField(default=now)

        class Meta:

            app_cache = BaseAppCache()

            app_label = "migrations"