adjust south to Django 1.5 custom user

south.py

from django.contrib.auth import get_user_model

User = get_user_model()

('user', self.gf('django.db.models.fields.related.ForeignKey')(to=orm["%s.%s" % (User._meta.app_label, User._meta.object_name)])),

"%s.%s" % (User._meta.app_label, User._meta.module_name): {
'Meta': {'object_name': User.__name__},
},

'user': ('django.db.models.fields.related.ForeignKey', [], {'to': u"orm['%s.%s']" % (User._meta.app_label, User._meta.object_name)})