Support access organization by subdomain

[leduythuccs]

Description

Now we can access organizations by subdomain. For example: team-bedao.vnoi.info will be equal to https://oj.vnoi.info/organization/team-bedao

Type of change: new feature

What

• Added a Middleware to get the org slug from subdomain, and attach it to request instance
• Override the navbar to redirect to org page instead of the normal page

How

• Just add judge.middleware.OrganizationSubdomainMiddleware to your middleware list:

MIDDLEWARE += (
    "judge.middleware.OrganizationSubdomainMiddleware",
)

• You might want to whitelist your domain/subdomain so that the middleware doesn't see it as a org slug. For example, vnoj is deployed at oj.vnoi.info, so we want to whitelist oj.

VNOJ_IGNORED_ORGANIZATION_SUBDOMAINS += ['oj']
# actually `oj` already whitelisted, this is just for example

UI

The old UI (without subdomain) is not changed. The UI with subdomain is here:

• Navbar and problem list:

- Contests list: - Submissions list:

Note: because the team-bedao doesn't have any submissions, so i used a random org for the above image

Why

• With this, each organization page will look more legit

How Has This Been Tested?

• Tested on my local, with my own domain

By submitting this pull request, I confirm that my contribution is made under the terms of the AGPL-3.0 License.

[leduythuccs]

I didn't add the middleware to the default settings on purpose