GetLine(): Add expanded type support.

[steviesama]

Currently, it only supports: string, float32/64, and int...which covers my use-case, but I'd like to cover future situations, and anyone that might find this code useful.

Below is a cross-section link of where the type switch is located:

jsonbuilder/jsonbuilder.go

Lines 60 to 69 in 62be5b5

	switch value.(type) {
	case string:
	return data + fmt.Sprintf("\"%s\"%s\n", EscapeJson(value.(string)), commaString)
	case float32:
	return data + fmt.Sprintf("\"%f\"%s\n", value, commaString)
	case float64:
	return data + fmt.Sprintf("\"%f\"%s\n", value, commaString)
	default:
	return data + fmt.Sprintf("%d%s\n", value, commaString)
	}