Make startup scripts optional

To optimize the application boot time the startup scripts can now be
disabled by an ENV variable. The default when the variable is not set,
is to run the startup scripts. This means that the default behaviour is
not changed from earlier releases.

docker/docker-entrypoint.sh

@@ -39,10 +39,14 @@ if not User.objects.filter(username='${SUPERUSER_NAME}'):
     Token.objects.create(user=u, key='${SUPERUSER_API_TOKEN}')
 END
 
-for script in /opt/netbox/startup_scripts/*.py; do
-  echo "⚙️ Executing '$script'"
-  ./manage.py shell --interface python < "${script}"
-done
+if [ "$SKIP_STARTUP_SCRIPTS" == "true" ]; then
+  echo "☇ Skipping startup scripts"
+else
+  for script in /opt/netbox/startup_scripts/*.py; do
+    echo "⚙️ Executing '$script'"
+    ./manage.py shell --interface python < "${script}"
+  done
+fi
 
 # copy static files
 ./manage.py collectstatic --no-input