Do not flush output of node server in journalctl

After some time the journal will become unreadable since the stdout of
server prints every request. This may not be useful, let this outputs
being shown only when running outside the server

Signed-off-by: Bruno Bottazzini <bruno.bottazzini@intel.com>

scripts/units/soletta-dev-app-server.service.in

@@ -2,6 +2,7 @@
 Description=Run Soletta Development Application server
 
 [Service]
+StandardOutput=null
 ExecStart=/usr/bin/NODE_BIN_NAME PATH/server/app.js 1> /dev/null 2>&1
 Environment="NODE_ENV=production"