Add Rules integration for register & login

Liking this route.

Just ignore that patch :)
Here is adding the actions with an inc file and triggering the events in the module.

Testing went well with this.

Possible useful spot.

...
        // Retrieve user mapping and attempt to log the user in.
        $ext_user = user_external_load($authname);

        if (module_exists('rules')) {
          rules_invoke_event('simplesamlphp_auth_rules_event_extlogin', $authname);
        }
...

I need to insert an authmap entry in one circumstance.