NoticeSetting.medium should be IntegerField instead of CharField

[ptone]

When the model is validated, the to_python of the charfield returns the value '0' which is not a valid choice key.

This trips up django.db.models.fields.Field.validate and causes any modelform for this model to fail submission (including in the admin).

see also:

https://code.djangoproject.com/ticket/20800

for why this took me more than a second to debug

[paltman]

@ptone thanks for this, somehow i had missed it and just not logged onto Freenode and got your message (I use a bouncer). I'll look into this over the next week.

[andrenerd]

the same thing...

[xaralis]

+1 On this. It's quite simple fix, i can send a PR if interested.

[sherzberg]

I would rather change the load_backends function to not use integer ids to represent the medium.

If you rearrange the backends, this would break user setttings. I propose we use either a required name attribute on a backend, or the full dotted class name.

Thoughts?

EDIT: actually, can we just use the label of the backend?

default_backends = [                                                                                
     ("email", "notification.backends.email.EmailBackend"),                                          
]