create a settings table for site-specific configuration in the database

[mhl]

In order to make it easier to configure a new YourNextRepresentative instance without having to edit files, we'd like to move some of the settings in conf/general.yml into a new settings table.

For example, we would want this to include these settings:

• The country that this site is for
• The default language and timezone
• DATE_FORMAT
• SUPPORT_EMAIL
• GOOGLE_ANALYTICS_ACCOUNT
• TWITTER_USERNAME
• RESTRICT_RENAMES
• NEW_ACCOUNTS_ALLOWED
• EDITS_ALLOWED
• HOIST_ELECTED_CANDIDATES
• DD_MM_DATE_FORMAT_PREFERRED *

... and possibly others.

• https://github.com/mysociety/yournextrepresentative/pull/918 would remove this setting anyway

Some questions to address here:

• Should these settings be related to a Site from the sites framework via a foreign key? (Probably.)
• Is there any point in using an existing app to manage this? (Probably not.)

[struan]

Having had a bit of a look at existing apps this looks to be the best of them:

https://django-usersettings2.readthedocs.io/en/latest/readme.html

in that it uses the sites framework and has some handy caching and middleware features. It also is the only one I found that supported Python 3. We would need to build an interface on top of it (it does have an admin interface built in)

[wfdd]

I'm trying this out right now. A couple of observations/suggestions:

• I don't think there's actually a 'Date Format' setting.
• Members of the 'Can Edit Settings' user group should be shown a link to the /settings page, perhaps next to the mod queue counter.
• In /settings, the hoist candidates checkbox's label is not clickable; <label id="id_HOIST_ELECTED_CANDIDATES"> should be <label for="id_HOIST_ELECTED_CANDIDATES">.

[wfdd]

I don't think 'Maximum party list size to display on post page' is the right label for CANDIDATES_REQUIRED_FOR_WEIGHTED_PARTY_LIST - you might've confused it with the 'default party list members to show' election setting.