Add opt-in option for tracking

[ZinRicky]

At the moment server tracking is on by default and there is no tracker entry in the config file either: one has to manually add tracker: false. As this behaviour doesn't seem right to be the default, can you please add at least the explicit entry in the default config file?

[slipcor]

Thanks for bringing this to my attention. This tracker is not even active (any more?). The only tracker I use is bStats which has a central disabling config :)

I will remove this sentence everywhere because this tracker is not present in the plugin!

Edit: I will update the text block with information about bStats!