let mailboxes reference os users

- refer to osuser instead of own home, uid and gid entries in mailboxes
- add data and schema migrations

gnuviechadmin/managemails/models.py

@@ -5,6 +5,8 @@ from django.utils.translation import ugettext as _
 from passlib.hash import sha512_crypt
 from model_utils.models import TimeStampedModel
 
+from osusers.models import User as OsUser
+
 
 @python_2_unicode_compatible
 class MailDomain(TimeStampedModel, models.Model):
@@ -31,11 +33,9 @@ class ActivateAbleMixin(models.Model):
 
 @python_2_unicode_compatible
 class Mailbox(ActivateAbleMixin, TimeStampedModel, models.Model):
+    osuser = models.ForeignKey(OsUser)
     username = models.CharField(max_length=128, unique=True)
     password = models.CharField(max_length=255)
-    home = models.CharField(max_length=255)
-    uid = models.PositiveSmallIntegerField()
-    gid = models.PositiveSmallIntegerField()
 
     class Meta:
         verbose_name = _('Mailbox')