Configurable logout redirect

[Justin Hayes]

The system used to redirect to the LSF website when logging out.

However now that the site is shared between 2 clubs I've had to turn that off for obvious reasons.

Need to make the redirect configurable so system admins can choose the redirect target (or not to redirect at all)

[Justin Hayes]

Will sort this as part of Issue #10

[Justin Hayes]

Pretty much done

[Justin Hayes]

Live