Add duniter system user for service

release/extra/debian/package/DEBIAN/postinst

@@ -34,6 +34,10 @@ if [[ -d $DUN_SOURCES/node ]]; then
   cd $DUN_SOURCES
   cd node/bin/
   ln -s ../lib/node_modules/npm/bin/npm-cli.js ./npm -f
+  # Add duniter user for service
+  mkdir -p /var/lib/duniter
+  adduser --system --quiet --home /var/lib/duniter --no-create-home --disabled-password --group duniter
+  chown duniter:duniter /var/lib/duniter
 fi
 # Else will execute with environment node