Add script to provide dev shell

dev/tools/initfile.sh

@@ -0,0 +1,4 @@
+pip install -e /tmp/work/plugin
+printf 'certbot_plugin_gandi:dns_api_key=%s\n' $GANDI_API_KEY > /tmp/config.ini && chmod 400 /tmp/config.ini 
+echo 'Example: certbot certonly --test-cert -a certbot-plugin-gandi:dns --certbot-plugin-gandi:dns-credentials /tmp/config.ini -d domain.com'
+exec /bin/sh