Support nginx

[jlicht]

Support nginx as a standalone webserver, in addition to Apache.

The current installation procedure depends on creating rewrite rules that reportedly work differently in Apache and Nginx. We requires testing the plugin with nginx, and identifying any code/installation/documentation changes.

See also: #49 and #50

[zjalexander]

Hi, over at critical-distance.com we are trying to use Amber but we currently have the problem hit over at issue #40 with Amber v 1.4.4 and nginx/1.17.0 . As a site with an explicitly archival mission we are pretty desperate to get this up and running to the point where we are starting to think about changing platforms to a setup that would support Amber better.

Is this on the roadmap or under active consideration at all?