Added Exception Log and fixed Google provider

[LorenzoRogai]

Added Exception Log on the _authenticate function

Added the support for Google provider, Google now returns an array with multiple emails. The script will now take the first one. This should prevent newUser from firing on each Google oAuth 2 login

[Spriz]

I personally think checking whether $data[$this->config('fields.username')] is an array or not is more suitable :-) This doesn't respect configurations neither.