Changed the update script

The script now wait for the user to open serial port enforcing the fact that the user see the update message
and acknowledge the FW update.

Author: maidnl

examples/updateExpansionFw/updateExpansionFw.ino

@@ -220,7 +220,8 @@ void updateTask() {
 void setup() {
 /* -------------------------------------------------------------------------- */    
   Serial.begin(115200);
-  delay(2000);
+  while(!Serial) {
+  }
 
   Serial.println("\n**** OPTA Expansions Updater sketch ****\n");