add reflect struct field on validate error

[ivybridge-3c33]

add reflect on fields

use case:
I've added reflect.StructField for using for getting a tag for using my own custom validate message and getting the field name from the language
example use from my own project

	type test struct {
		Title string `validate:"required" json:"title" lang_key:"title"` // ex language of title = "banana"
	}
	s := test{}
	err := validate.Struct(s)
	if validate, ok := err.(*validator.InvalidValidationError); ok {
		panic(validate)
	}

	errorsFields := make(map[string][]string, 0)
	for _, validate := range err.(validator.ValidationErrors) {
		fe := validate.ReflectStructField()
		fieldName := strings.Replace(fe.Tag.Get("json"), ",omitempty", "", 0)
		if _, ok := errorsFields[fieldName]; !ok {
			errorsFields[fieldName] = make([]string, 0)
		}
		msg := ""
		switch errTagName := validate.Tag(); errTagName {
		case "regexp":
			// format :"%s invalid format blablabla"
			msg = i18n.ParseT(ct, "validator.regexp", i18n.ParseT(ct, "test."+fe.Tag.Get("lang_key"))) // banana invalid format blabla
		}
		errorsFields[fieldName] = append(errorsFields[fieldName], msg)
	}

@go-playground/validator-maintainers

[coveralls]

coverage: 74.306% (+0.02%) from 74.291%
when pulling 6074805 on fullmoon-tech:reflex-struct-field
into a947377 on go-playground:master.

[deankarn]

@ivybridge-3c33 I like the idea of grabbing struct field, I wonder if it might be confusing though for when the validation is not a struct field.

I wonder if there would be a way for it to work with struct fields and regular ones also?