Added FIXME for remind set up bridge discovery on linkd
Moved to core.Criteria to avoid deprecated OnmsCriteria

The EnhancedLinkdService use now Criteria instead of
deprecated OnmsCriteria, added a test
Added a control for ospf link discovery to check if it is enabled
Removed an unused import from OspfDiscovery
Added IsIsElement to Object model
Added IsIs discovery to enhanced linkd

First step added IsIsElement