New port: www/sws

sws was born out of a project requirement for a small universal Web
server that could run on any POSIX platform to serve static
content. Since it is written in /bin/sh it should run on any
BSD/GNU-Linux/Unix system.

PR: 197694
Differential Revision: https://reviews.freebsd.org/D1988
Reviewed by: swills
Approved by: swills (mentor)