Deploy Django branch

[jpmckinney]

https://docs.djangoproject.com/en/3.0/howto/deployment/

Go through checklist, notably:

• https://docs.djangoproject.com/en/3.0/ref/databases/#persistent-connections
  https://pypi.org/project/dj-database-url/
• https://docs.djangoproject.com/en/3.0/ref/templates/api/#template-loaders
• https://docs.djangoproject.com/en/3.0/topics/logging/
• https://docs.djangoproject.com/en/3.0/howto/error-reporting/

Set environment variables from Salt:

• Django variables
• KINGFISHER_PROCESS_ENV=production
• KINGFISHER_PROCESS_SECRET_KEY=
• STATIC_ROOT if needed
• KINGFISHER_PROCESS_SECURE_HSTS_SECONDS=31536000 (1 year) after testing on smaller values

Miscellaneous:

• PostgreSQL: Change timezone to 'UTC'
• Use Systemd to monitor workers (we already use it to monitor Scrapyd)

python manage.py migrate should create:

CREATE TABLE public.django_migrations (
    id integer NOT NULL,
    app character varying(255) NOT NULL,
    name character varying(255) NOT NULL,
    applied timestamp with time zone NOT NULL
);
CREATE SEQUENCE public.django_migrations_id_seq
    AS integer
    START WITH 1
    INCREMENT BY 1
    NO MINVALUE
    NO MAXVALUE
    CACHE 1;
ALTER SEQUENCE public.django_migrations_id_seq OWNED BY public.django_migrations.id;
ALTER TABLE ONLY public.django_migrations ALTER COLUMN id SET DEFAULT nextval('public.django_migrations_id_seq'::regclass);
ALTER TABLE ONLY public.django_migrations
    ADD CONSTRAINT django_migrations_pkey PRIMARY KEY (id);

We can later manually drop:

• alembic_version
• transform_upgrade_1_0_to_1_1_status_release
• transform_upgrade_1_0_to_1_1_status_record

As follow-up to #242, we can also drop:

• release_check_error
• record_check_error

[jpmckinney]

We deployed this to the data registry, and will deploy it to a fresh server for the helpdesk (rather than the more difficult original plan to migrate the deployment to the new version).

• PostgreSQL uses UTC.
• Docker is used to monitor workers.
• The tables listed as being droppable don't exist in the new version.

Follow-up issues: open-contracting/deploy#331