refactor CookieOverflow

[skojin]

Check cookie size when set it, not in middleware

Purpose

Instead of check cookie size at end of request in middleware check it when set it.

Description

Two props:

1. more simple code
2. error stack trace will show place where bad cookie was set

Extra

Rails do in same way, check when cookie is set. One difference rails check size only of encrypted/signed cookies. Plain cookies size not checked.

In this commit I still check size of all cookies, encrypted and raw.
Possible we not need to check size of raw cookies.

[paulcsmith]

Thank you so much for handling this! I'll merge for now and see if I can test it out and make sure it all works in production apps. It can be tricky to handle edge cases in cookie :P

@jwoertink would you mind giving this a try one some of your projects to make sure cookies are still working correctly?