Update entrypoint.sh so proxy can listen on a port other than 8080

[binduwavell]

Prior to this change, if the proxy is configured to listen on say port 80 and you goto http://localhost/share, you will be redirected to http://localhost:8080/share/page/. This is because nginx is fowarding localhost:8080 to Share's Tomcat and when Share creates fully qualified URLs, it includes the port that should be hidden by nginx.

[binduwavell]

@hi-ko on Discord suggested adding the following headers as well:

proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header X-Forwarded-Proto $scheme;

These are apparently default on the ubuntu nginx configuration and could help with other relaying issues.

I'm happy to update my PR with this information or possibly add above the location level so it applies to all "routes"... I figured I'd wait for feedback before making any changes.