Do you know the difference between `$cookies` and `$cookieStore`?
I've tried `$cookieStore` but it can not read and write browser cookies, then I tried `$cookies` and it works.
I guess here we do not need `$cookieStore.remove('userid');` because actually it won't remove browser cookies.
And even we do not remove the cookie, it is OK.

I guess `$cookieStore` means use cookie to do some storage, but this cookie may be not visible and responsible to the server.