Visitor IP checking

[ghost]

As now, Visitor take into consideration visitors who has the same IP if they don't have the same useragent, E.G :

Visitor shouldn't create a new entry into the database if they has the same IP, even if it's not the same useragent.

[JN-Jones]

I'm not sure here. If I'd only check the IP all users behind a dhcp server would be handled as one. Let me check something

[JN-Jones]

I think it's ok atm: a session id is generated and saved for every user (including guests) so when you're always using the same browser only one entry is added. But when you're using a different browser (or another PC behind a dhcp) a new entry is added as the sid isn't set