Adding dynamic rewrite of nginx during entrypoint to support TARGET_PORT

Signed-off-by: James Ketrenos <james_git@ketrenos.com>

entrypoint.sh

@@ -1,5 +1,9 @@
 #!/bin/bash
-nginx
+
+if [[ "${TARGET_PORT}" != "" ]]; then
+  sed -i -e "s,8123,${TARGET_PORT},g" /etc/nginx/sites-enabled/default
+fi
+/usr/sbin/nginx
 
 mkdir -p /var/lib/shellinabox
 chmod a+rwX /var/lib/shellinabox
@@ -19,4 +23,4 @@ else
   { while true; do npm start ; sleep 3 ; done ; } &
   cd /website/client
   npm start
-fi
+fi