Bail on first error

[jcobhams-cp]

Would it be possible to return the error bag on the first failure as opposed to running all the rules.

1. Bail when the first rule in a ruleset for a field fails
   example:

rules := govalidator.MapData{
		"email": []string{"required"},
		"password": []string{"required"},
		"some_field": []string{"bail", "required", "in:something,somethingelse"},
	}

2. Bail when the first rule for the entire validation fails.

opts := govalidator.Options{
		Request:         r        // request object
		Rules:           rules,    // rules map
		Messages:        messages, // custom message map (Optional)
		RequiredDefault: true,     // all the field to be pass the rules
                 BailFirstError: true //returns the error bag with only one item
	}