Fixes: There is no Cookie Prefix on this cookie

[Fraenkiman]

Fixes #155

• Creates a more robust cookie with __secure- prefix and increases the acceptance of compatible browsers.

This prefix is the more relaxed in terms of the restrictions it applies but is still useful. You simply prefix your cookie and a compliant browser will enforce it:

Set-Cookie: __Secure-sess=123; path=/; Secure

The __secure prefix signals to the browser that the SecureAttribute is required.