Project ready to run from school Linux

[linhtng]

@pixelsnow @wengcychan @djames9
Main changes:

• Adapt ALLOWED_HOSTS and CSRF_TRUSTED_ORIGINS in backend settings
• Add NGINX_PORT to .env file
• In the codebase, replace the hard-coded NGINX_PORT by the one fetched from .env file as much as possible. There are still 2 places in which it is still hard-coded, which is in nginx.conf file. It looks troublesome to set up script for that so I just leave it be.

Testing:
Run make with the newest .env and see that everything works.

[liocle]

Looks good to me! : ) I have tested to access nginx with the port in the .env file, both localhost and the loopback address were accessible. Please someone else who may be more knowledgeable in Python check the code as well: @pixelsnow @wengcychan @djames9 ?

[linhtng]

As I learnt from @liocle that we can eval from cluster 4 on computers where port 443 works, this PR is no longer needed.