Inherit _isLogged property if terror instance is passed to createError

[narqo]

var err1 = Terror.createError('MY_INNER_ERROR', new Error('my error'));
err1.log();

var err2 = Terror.createError('MY_ERROR', err1);
err2.log();

I'm not sure, but currently there is no public API to prevent err2 from being logged as err1 had been logged previously.