WebAccess: IP-based rules and offline user fix

* Correctly handles a corner case of
  access_control_firerole.acc_firerole_check_user() where, when
  checking a guest user created with collect_user_info(None) (hence
  having the 'remote_ip' key set to '') against an IP-based FireRole
  rule, would have raised an unhandled exception. (closes #1233)

* Introduces a new register_exception() statement in order to early
  discover troubles with acc_firerole_check_user().
Merge branch 'maint-0.99' into maint-1.0

* maint-0.99:
  WebAccess: IP-based rules and offline user fix

Conflicts:
	modules/webaccess/lib/access_control_firerole.py
	modules/webaccess/lib/access_control_firerole_tests.py