Add a check to prevent users from running jahiaServer.bat the first installation time

Add a check (either a TXT msg in the console or an HTML error screen or even better both) when starting with jahiaServer.bat the very first time. This is not so obvious that you need to launch jahiaInstallation.bat and I presume lots of users are launching the wrong batch file the first time... and there is no indication at all that this is the wrong one (and if you have IE already started, the redirect starts before Jahia is even luanched resulting in an ugly Page can not be displayed with the bad url.

So already quite a bad user experience for a Jahia beginner which could be easily avoided by only checking the presence of the configured jahia.properties file at the very beginning and displaying some msg in the console to launche the other batch file.