After updating to new version, the web UI is blank, needs cache cleared to fix

[mofojed]

Description
Sometimes after an update, the web UI is blank. You need to clear the cache to fix it

Steps to reproduce

1. Start on an older version. Start up the stack and open the web UI (http://localhost:10000)
2. Shutdown the stack, then git pull to the latest version
3. Start up the stack and open the web UI

Expected results
3. The Web UI appears

Actual results
3. A blank screen appears

After clearing the browser cache or doing a hard refresh, the web UI appears correctly

[mofojed]

It looks like index.html is getting cached by nginx incorrectly. It is generating the tag based on the modified date and the content length: https://github.com/nginx/nginx/blob/41a241b3ef74dbbe3d82ab2ebbe682919e4a0b90/src/http/ngx_http_core_module.c#L1698

However, the modified date for each pack downloaded from npm is always the same (Oct 26, 1985), so the resulting etag is the same. npm does this intentionally as per this commit: npm/npm@58d2aa5#diff-fe919d90e71d3a699df92b186fdbee6b

Either we need to have that modified date updated when extracting the zip contents, or disable caching entirely on index.html (chunks should still be cached).