Bugs correction in NetworkModelService

Bugs correction in NetworkModelService

Modify NetworkModelService class to add deleteOpenROADMnode function
to be able to :
- delete OpenROADM node portmapping
- delete OpenROADM node topologies (clli-network, openroadm-network,
openroadm-topology) created in datastores.
Modify NetConfTopologyListener OnDataTreeChanged to allow Portmapping
working in Oxygen. This issue is similar to the previous commit
"Bug correction in RendererNotificationImpl"

JIRA: TRNSPRTPCE-18
Change-Id: Ib529aff433c14c1c103f39be158b2a7746cb0cef
Signed-off-by: Martial COULIBALY <martial.coulibaly@gfi.fr>