Description: Adds a new middleware to help with cookie name changes. It uses the idea of expand and contract, where after we've changed the name, the middleware allows up to accept either a cookie with new name (given higher priority when both are present) or cookie with old name.

This is also helpful when changing domain of a cookie.

impacts: developers, users(anyone that has cookies)
Change depends on django setting changes. See CookieNameChange middleware for more info.