Ticket validation can be skipped if uri filter properties don't cover a URL

[sbearcsiro]

Some apps may not want to force a login but will want to validate any CAS ticket call backs. In the v3.1 of the plugin, the CAS validation filter is wrapped by the URI filter. This prevents tickets being validated and the user principal being established on URL paths that are outside the URI filters.

We should provide an option for apps to opt out of wrapping the validation filter, so that user's can login from any URL.

Note that v3.2 of the auth plugin removes the UriFilter from the CAS validation filter altogether so this change will also ease the upgrade path from v3.1 to v3.2