Add SCRIPT_NAME prefix to images directory path

[chuckination]

We need to at the SCRIPT_NAME prefix to the images directory to properly handle serving the flag images from a UWSGI + NGINX subdirectory path.

[furlongm]

Can you check if this is still required with the latest release?

[septatrix]

I would instead recommend dropping the flag images and replacing them with unicode flag symbols. One simply has to replace the two letter country codes with their "regional indicator symbol letter" (simply add an offset to the codepoint) and then gets the corresponding flag symbol. There is an explanation on emojipedia

[furlongm]

The unicode symbols sound like a great idea - I'd be happy to consider a PR for that against the latest branch.