attemptsField should be selected when selectFields is specified

[dongyingtao]

When selectFields option is specified and limitAttempts is set to true, the wrong password authentication will failed with CAST error. This is because the attemptsField is not really selected by the query. When it tries to increment attempts by 1, that would always be (undefined+1)=>NaN which cannot be cast to a Number.

As hashField, the attemptsField is internally used by passport-local-mongoose. When it is necessary, passport-local-mongoose should add it to the selected fields like hashField and saltField. This should be a simple fix.