Don't specify the port in nginx absolute redirects

* Include `port_in_redirect off;` in the default server block for
  Nginx. Nginx listens to port 8080 by default in Openshift. But the
  standard public route is on port 80. When Nginx redirects it will
  append port 8080 to the public route by default, hence leading to a
  'server not found' error. `port_in_redirect off;` instucts Nginx to
  not specify the port in redirects. An example would be when visiting
  directories that are served as part of a static site without
  including a trailing slash (`http://server/directory` instead of
  `http://server/directory/`). Nginx will automatically redirect to the
  URL with the trailing slash and the port becomes an issue.

assemble

@@ -18,6 +18,12 @@ mv /tmp/src /tmp/src-original
 cd /tmp/src-original/
 /opt/rh/rh-python36/root/usr/bin/mkdocs build --clean --site-dir /tmp/src/
 
+# Configure nginx to not specify the port in absolute redirects.
+mkdir /tmp/src/nginx-default-cfg/
+cat <<EOF> /tmp/src/nginx-default-cfg/redirect.conf
+port_in_redirect off;
+EOF
+
 # Go back to the current directory.
 cd $cwd