Custom cookie name

[Yeenot]

I would like to set a custom key/name for the cookie instead of the name 'locale'.

My solution is that change 'locale' on LocaleCookieRedirect middleware to a config variable with a default of 'locale' so that it can be customized.

Thank you for the awesome package :)

[okovpashko]

Also would be great to change the cookie domain and httponly flag for the cases when we need to share it with the other services on the same root domain.