Changed all status to start with Uppercase letters, made 3 properties required. Changed all the status to start with Uppercase letters because they are publicly visible. Also changed required=True to False for created_by, modified_by property to allow site admin to create and modify tasks. Also changed required=True to False for history to allow history not to be written until the task is published.

from django.contrib import admin
from django.contrib.sites.models import Site


class SiteAdmin(admin.ModelAdmin):
    list_display = ('domain', 'name')
    search_fields = ('domain', 'name')

admin.site.register(Site, SiteAdmin)