LDAP SSO: Set LDAP cookie lifetime to something other than immediate by default to stop SSO loops

Enabling SSO on a site that's not properly configured will cause SSO loops and makes your site unusable until you move the SSO module out of the modules folder.

Setting the cookie lifetime to something other than 'immediate' stops the SSO loops because a cookie is set that tells the SSO module that a login has been attempted (and failed).

It'd be good if the cookie lifetime was something other than 'immediate' by default to prevent people crashing their sites when they first play around with the SSO module (sometimes LDAP stuff can be a bit fiddly) - or maybe make it really obvious in the description text? Open to suggestions and can provide a patch.